tag:theconversation.com,2011:/nz/topics/magma-19179/articlesMagma – The Conversation2023-12-19T21:59:56Ztag:theconversation.com,2011:article/2201932023-12-19T21:59:56Z2023-12-19T21:59:56ZVolcanic eruption lights up Iceland after weeks of earthquake warnings − a geologist explains what’s happening<p>Lava erupted through a fissure in Iceland’s Reykjanes Peninsula on Dec. 18, 2023, shooting <a href="https://en.vedur.is/about-imo/news/a-seismic-swarm-started-north-of-grindavik-last-night">almost 100 feet (30 meters)</a> in the air in its early hours.</p>
<p>Icelanders had been anticipating an eruption in the area for weeks, ever since a <a href="https://en.vedur.is/about-imo/news/a-seismic-swarm-started-north-of-grindavik-last-night">swarm of thousands of small earthquakes</a> began on Oct. 23 northeast of the fishing town of Grindavík, signaling volcanic activity below. </p>
<p>In the days that followed those first rumblings, a series of small rifts opened under the town, breaking streets, rupturing utility lines and tilting houses. GPS stations detected the <a href="https://en.vedur.is/about-imo/news/earthquake-activity-in-fagradalsfjall-area">ground sinking and rising</a> over a large area.</p>
<p>Geologists from the <a href="https://en.vedur.is/about-imo/news/a-seismic-swarm-started-north-of-grindavik-last-night">Icelandic Met Office</a> interpreted the events as evidence that a basalt dike – pressurized magma that forces its way into a fracture – had intruded under Grindavík. The activity there had tapered off by early December, but 2.5 miles (4 kilometers) north of town, the ground under the <a href="https://www.verkis.com/projects/energy-production/geothermal-energy/nr/936">Svartsengi</a> geothermal power plant was moving.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/566683/original/file-20231219-19-6waspp.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A map shows the location of the fissure." src="https://images.theconversation.com/files/566683/original/file-20231219-19-6waspp.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/566683/original/file-20231219-19-6waspp.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/566683/original/file-20231219-19-6waspp.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/566683/original/file-20231219-19-6waspp.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/566683/original/file-20231219-19-6waspp.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/566683/original/file-20231219-19-6waspp.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/566683/original/file-20231219-19-6waspp.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The location of the fissure where magma erupted starting Dec. 18, 2023, a few miles from the town of Grindavík and just east of Svartsengi power plant and ajacent Blue Lagoon thermal spa.</span>
<span class="attribution"><a class="source" href="https://en.vedur.is/about-imo/news/a-seismic-swarm-started-north-of-grindavik-last-night">Icelandic Met Office</a></span>
</figcaption>
</figure>
<p>The ground had dropped 10 inches (25 centimeters) as the basalt dike filled, but then it began to rise in a broad dome, indicating that magma was reinflating and repressurizing the magma chamber. The result was the nearby eruption on Dec. 18.</p>
<p>If the fissure continues to propagate to the south, or if a large volume of lava erupts, the evacuated town of Grindavík, with a population of around 3,500, may be in danger. The lava could also spill to the northwest toward the power plant, although the utility built rock walls to try to divert lava flows.</p>
<figure class="align-center ">
<img alt="An aerial photo shows the lights of Grindavík and glow of the eruption very nearby." src="https://images.theconversation.com/files/566707/original/file-20231219-25-zfbj7a.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/566707/original/file-20231219-25-zfbj7a.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=396&fit=crop&dpr=1 600w, https://images.theconversation.com/files/566707/original/file-20231219-25-zfbj7a.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=396&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/566707/original/file-20231219-25-zfbj7a.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=396&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/566707/original/file-20231219-25-zfbj7a.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=498&fit=crop&dpr=1 754w, https://images.theconversation.com/files/566707/original/file-20231219-25-zfbj7a.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=498&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/566707/original/file-20231219-25-zfbj7a.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=498&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">The evacuated town of Grindavík and a nearby geothermal power plant are still at risk.</span>
<span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/news-photo/the-evacuated-icelandic-town-of-grindavik-is-seen-as-smoke-news-photo/1860420658?adppopup=true">Viken Kantarci/AFP via Getty Images</a></span>
</figcaption>
</figure>
<p>Iceland is known as “the land of fire and ice” for a reason. Its residents have learned over centuries to live with its overactive geology.</p>
<p>The reason for Iceland’s volcanism has two parts: One has to do with what geologists unimaginatively <a href="https://oceanexplorer.noaa.gov/facts/volcanic-hotspot.html">call a hot spot</a>, and the other involves giant tectonic plates that are pulling apart beneath the island. As <a href="https://scholar.google.com/citations?user=r8FqGBEAAAAJ&hl=en">a geologist</a>, I study both.</p>
<h2>Life on the edge of two tectonic plates</h2>
<p>When <a href="https://www.iris.edu/hq/inclass/animation/plate_tectonic_theorya_brief_history">plate tectonic theory</a> was emerging in the 1960s, geologists realized that many volcanoes are located in zones where tectonic plates meet. Tectonic plates are gigantic chunks of Earth’s rigid outer layer that carry both continents and oceans and are constantly in motion. They <a href="https://www.usgs.gov/media/images/tectonic-plates-earth">cover the planet</a> like large pieces of a spherical jigsaw puzzle.</p>
<p>Many of these volcanoes are in subduction zones, like the Pacific’s <a href="https://education.nationalgeographic.org/resource/plate-tectonics-ring-fire/">Ring of Fire</a>, where thinner oceanic plates slowly sink into <a href="https://education.nationalgeographic.org/resource/mantle/">Earth’s mantle</a>. These are the postcard stratovolcanoes like Mount Fuji, in Japan, or Mount Rainier, outside of Seattle. Because of their high gas content, they tend to erupt catastrophically, shooting ash high into the atmosphere with the energy of nuclear bombs, as <a href="https://www.usgs.gov/volcanoes/mount-st.-helens/science/1980-cataclysmic-eruption">Mount St. Helens did in 1980</a>.</p>
<p>A second, typically quieter kind of volcano forms <a href="https://oceanexplorer.noaa.gov/facts/mid-ocean-ridge.html">where plates pull apart</a>.</p>
<p>The volcanic activity near Grindavík is directly related to this kind of plate tectonic motion. The mid-Atlantic ridge between the Eurasian and North American plates cuts right through that part of the island.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/559688/original/file-20231115-22-mdyae8.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A map shows where the earthquakes are taking place in a southwest peninsula and where the tectonic plates meet." src="https://images.theconversation.com/files/559688/original/file-20231115-22-mdyae8.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/559688/original/file-20231115-22-mdyae8.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=780&fit=crop&dpr=1 600w, https://images.theconversation.com/files/559688/original/file-20231115-22-mdyae8.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=780&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/559688/original/file-20231115-22-mdyae8.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=780&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/559688/original/file-20231115-22-mdyae8.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=980&fit=crop&dpr=1 754w, https://images.theconversation.com/files/559688/original/file-20231115-22-mdyae8.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=980&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/559688/original/file-20231115-22-mdyae8.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=980&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Iceland sits atop the meeting of two tectonic plates, the North American to the west and Eurasian to the east, indicated by the red line crossing the island. The maps show the earthquake swarms on Nov. 12-14, 2023.</span>
<span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/news-photo/an-infographic-titled-iceland-prepares-for-volcanic-news-photo/1782148842?adppopup=true">Yasin Demirci/Anadolu via Getty Images</a></span>
</figcaption>
</figure>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/559732/original/file-20231115-27-7uf0ky.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A map shows details of midocean ridges looking like seams on a baseball as they wind through the major oceans." src="https://images.theconversation.com/files/559732/original/file-20231115-27-7uf0ky.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/559732/original/file-20231115-27-7uf0ky.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=330&fit=crop&dpr=1 600w, https://images.theconversation.com/files/559732/original/file-20231115-27-7uf0ky.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=330&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/559732/original/file-20231115-27-7uf0ky.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=330&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/559732/original/file-20231115-27-7uf0ky.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=415&fit=crop&dpr=1 754w, https://images.theconversation.com/files/559732/original/file-20231115-27-7uf0ky.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=415&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/559732/original/file-20231115-27-7uf0ky.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=415&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">In the 1950s, cartographer Marie Tharp used echo soundings gathered by ships to develop the first map showing the ocean floor in detail. It clearly revealed the mid-ocean ridges. This hand-painted version of her map includes annotations showing hot spot tracks related to movement of the plates.</span>
<span class="attribution"><a class="source" href="https://www.loc.gov/">Heinrich C. Berann via Library of Congress; annotations by Jaime Toro</a></span>
</figcaption>
</figure>
<p>In fact, at <a href="https://guidetoiceland.is/connect-with-locals/jorunnsg/ingvellir-national-park">Thingvellir National Park</a> you can literally walk between the two tectonic plates. You can see the topographic scars of the rift in the long, linear valleys that extend to the northeast from Grindavík. They align with the swarms of earthquakes, the <a href="https://en.vedur.is/about-imo/news/bigimg/4511?ListID=0">ground deformation</a>, and the fissure eruption of 2023.</p>
<p>Where plates pull away from each other, the underlying mantle rises toward the surface to fill the gap, carrying its heat with it and moving into an area of lower pressure. Those <a href="https://www.e-education.psu.edu/rocco/node/1988">two processes</a> cause melting at depth and volcanic activity at the surface.</p>
<p>This is the <a href="https://en.wikipedia.org/wiki/Sheeted_dyke_complex">same process that creates new oceanic crust</a> underwater at mid-ocean ridges. After the magma solidifies as basalt rock, it will look like vertical walls intruded into the surrounding area.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/566733/original/file-20231219-19-4i4dgz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="The uplift is in a large area that includes a nearby power plant and the Blue Lagoon thermal spa." src="https://images.theconversation.com/files/566733/original/file-20231219-19-4i4dgz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/566733/original/file-20231219-19-4i4dgz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=552&fit=crop&dpr=1 600w, https://images.theconversation.com/files/566733/original/file-20231219-19-4i4dgz.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=552&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/566733/original/file-20231219-19-4i4dgz.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=552&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/566733/original/file-20231219-19-4i4dgz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=694&fit=crop&dpr=1 754w, https://images.theconversation.com/files/566733/original/file-20231219-19-4i4dgz.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=694&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/566733/original/file-20231219-19-4i4dgz.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=694&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">A map shows the uplift of the ground (bright red) north of Grindavík prior to the Dec. 18, 2023, eruption, as well as the extent of the new lava flow (black).</span>
<span class="attribution"><a class="source" href="https://en.vedur.is/">Icelandic Met Office</a></span>
</figcaption>
</figure>
<h2>Sitting on a hot spot</h2>
<p>In Iceland, the large volcanoes in the interior also <a href="https://doi.org/10.1016/j.epsl.2013.02.022">appear to be over a mantle plume</a>, <a href="https://theconversation.com/where-mauna-loas-lava-is-coming-from-and-why-hawaiis-volcanoes-are-different-from-most-195633">similar to Hawaii</a>.</p>
<p>This kind of volcano typically erupts basalt lava, which melts at very high temperature and tends to flow easily. Eruptions are generally not explosive because the runny lava allows gases to escape. </p>
<p>Exactly what causes hot material to rise at hot spots is still debated, but the most commonly accepted idea is that they are caused by plumes of super-heated rock that originate at the transition <a href="https://doi.org/10.1126/science.349.6252.1032">between Earth’s metallic core and rocky mantle</a>. Hot spots are a mechanism for the Earth to give off some of its <a href="https://www.sciencealert.com/earth-s-insides-are-cooling-faster-than-we-thought-and-it-will-mess-things-up">internal heat</a>.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/Hl1gfV-TdU0?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">How hot spots develop. Video by Volcano Museum.</span></figcaption>
</figure>
<p>Typically, fissure eruptions are not explosive. However, when lava that is 1,800 degrees Fahrenheit (about 1,000 degrees Celsius) hits water, the flash to steam can cause explosions that can scatter ash over a larger area. </p>
<h2>A silver lining of Iceland’s volcanoes</h2>
<p>Living in an active volcanic area has some advantages, particularly for energy.</p>
<p>Iceland derives 30% of its electricity from geothermal sources that use underground heat to drive turbines and produce power. It’s almost like a controlled version of a lava flow hitting the sea, and it helps make Iceland <a href="https://www.volts.wtf/p/whats-the-deal-with-iceland#details">one of the cleanest economies on earth</a>.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/559465/original/file-20231114-21-f3fk7c.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="People sit in an eggshell-blue lake surrounded by black lava rocks. Steam rises in the background." src="https://images.theconversation.com/files/559465/original/file-20231114-21-f3fk7c.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/559465/original/file-20231114-21-f3fk7c.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=758&fit=crop&dpr=1 600w, https://images.theconversation.com/files/559465/original/file-20231114-21-f3fk7c.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=758&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/559465/original/file-20231114-21-f3fk7c.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=758&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/559465/original/file-20231114-21-f3fk7c.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=953&fit=crop&dpr=1 754w, https://images.theconversation.com/files/559465/original/file-20231114-21-f3fk7c.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=953&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/559465/original/file-20231114-21-f3fk7c.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=953&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Iceland has a lot of natural hot springs, but its Blue Lagoon has an unusual origin linked to geothermal energy.</span>
<span class="attribution"><a class="source" href="https://unsplash.com/photos/people-swimming-on-hot-spring-near-mountain-during-daytime-jTeQavJjBDs">Photo by Jeff Sheldon on Unsplash</a>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<p>The <a href="https://www.verkis.com/projects/energy-production/geothermal-energy/nr/936">Svartsengi</a> hydrothermal plant uses the underground heat from the same magma chamber that is now erupting to provide hot water for several thousand homes, plus 75 megawatts of electricity.</p>
<p>That power plant is also part of the reason the <a href="https://www.bluelagoon.com/">Blue Lagoon</a> is so popular. When the power plant was built in 1976, the plan was to discharge its still hot wastewater into an adjacent low area, expecting that it would seep into the ground. However, the geothermal water was loaded with dissolved silica, which became solid minerals when the water cooled, creating an impermeable layer. A small lake began to form.</p>
<p>Because of its high silica content, the water in this lake is a spectacular blue color that inspired the creation of the geothermal spa. The Blue Lagoon is one of the top tourist attractions in the country.</p>
<p>Now the Blue Lagoon is at risk: Sometimes the volcano gives, sometimes it takes away.</p>
<p><em><a href="https://theconversation.com/pourquoi-leruption-volcanique-en-islande-na-rien-dune-surprise-les-explications-dun-geologue-220292">Lire en français</a></em></p>
<p><em>This is an updated version of an <a href="https://theconversation.com/volcanic-iceland-is-rumbling-again-as-magma-rises-a-geologist-explains-eruptions-in-the-land-of-fire-and-ice-217671">article published Nov. 15, 2023</a>.</em></p><img src="https://counter.theconversation.com/content/220193/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Jaime Toro works for West Virginia University. In the past, he has received funding from NSF, USGS and DOE.
</span></em></p>Iceland is known as ‘the land of fire and ice’ for a reason.Jaime Toro, Professor of Geology, West Virginia UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2104212023-07-26T16:51:04Z2023-07-26T16:51:04ZWe’ve discovered how diamonds make their way to the surface and it may tell us where to find them<figure><img src="https://images.theconversation.com/files/539502/original/file-20230726-21-jcon90.jpg?ixlib=rb-1.1.0&rect=17%2C0%2C5773%2C3820&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/natural-diamond-nestled-kimberlite-1608584494">Bjoern Wylezich / Shutterstock</a></span></figcaption></figure><p>“A diamond is forever.” That iconic slogan, coined for a <a href="https://www.thedrum.com/news/2016/03/31/1948-de-beers-diamond-forever-campaign-invents-the-modern-day-engagement-ring">highly successful advertising campaign in the 1940s</a>, sold the gemstones as a symbol of eternal commitment and unity. </p>
<p>But our new research, carried out by researchers in a variety of countries and <a href="https://www.nature.com/articles/s41586-023-06193-3">published in Nature</a>, suggests that diamonds may be a sign of break up too – of Earth’s tectonic plates, that is. It may even provide clues to where is best to go looking for them. </p>
<p>Diamonds, being the <a href="https://pursuit.unimelb.edu.au/articles/diamonds-the-hard-facts">hardest naturally-occurring stones</a>, require intense pressures and temperatures to form. These conditions are only achieved deep within the Earth. So how do they get from deep within the Earth, up to the surface? </p>
<p>Diamonds are carried up in molten rocks, or magmas, called <a href="https://www.britannica.com/science/kimberlite">kimberlites</a>. Until now, we didn’t know what process caused kimberlites to suddenly shoot through the Earth’s crust having spent millions, or even billions, of years stowed away under the continents.</p>
<h2>Supercontinent cycles</h2>
<p>Most geologists agree that the explosive eruptions that unleash <a href="https://www.science.org/doi/abs/10.1126/science.1206275">diamonds happen in sync</a> with the supercontinent cycle: a recurring pattern of landmass formation and fragmentation that has defined billions of years of Earth’s history. </p>
<p>However, the exact mechanisms underlying this relationship are debated. Two main theories have emerged. </p>
<p>One proposes that kimberlite magmas <a href="https://www.sciencedirect.com/science/article/abs/pii/S0024493709002758">exploit the “wounds”</a> created when the Earth’s crust is stretched or when the slabs of solid rock covering the Earth – known as tectonic plates – split up. The other theory <a href="https://www.nature.com/articles/s41467-019-13871-2#:%7E:text=Using%20inferences%20from%20older%2C%20smooth,dense%20lower%20lithosphere%2C%20so%20that">involves mantle plumes</a>, colossal upwellings of molten rock from the core-mantle boundary, located about 2,900km beneath the Earth’s surface.</p>
<figure class="align-center ">
<img alt="Structure of the Earth." src="https://images.theconversation.com/files/539551/original/file-20230726-21-tgwt8l.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/539551/original/file-20230726-21-tgwt8l.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=418&fit=crop&dpr=1 600w, https://images.theconversation.com/files/539551/original/file-20230726-21-tgwt8l.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=418&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/539551/original/file-20230726-21-tgwt8l.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=418&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/539551/original/file-20230726-21-tgwt8l.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=526&fit=crop&dpr=1 754w, https://images.theconversation.com/files/539551/original/file-20230726-21-tgwt8l.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=526&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/539551/original/file-20230726-21-tgwt8l.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=526&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">A representation of the internal structure of the Earth.</span>
<span class="attribution"><a class="source" href="https://www.usgs.gov/media/images/earth-cross-section">USGS</a></span>
</figcaption>
</figure>
<p>Both ideas, however, are not without their problems. Firstly, the main part of the tectonic plate, <a href="https://education.nationalgeographic.org/resource/lithosphere/">known as the lithosphere</a>, is incredibly strong and stable. This makes it difficult for fractures to penetrate, enabling magmas to flush through. </p>
<p>In addition, many kimberlites don’t display the chemical “flavours” we’d expect to find in rocks derived from mantle plumes.</p>
<p>In contrast, kimberlite formation is thought to involve exceedingly low degrees of mantle rock melting, often less than 1%. So, another mechanism is needed. Our study offers a possible resolution to this longstanding conundrum.</p>
<p>We deployed statistical analysis, including machine learning – an application of artificial intelligence (AI) – to forensically examine the link between continental breakup and kimberlite volcanism. The results of our global study showed the eruptions of most kimberlite volcanoes occurred 20 to 30 million years after the tectonic breakup of Earth’s continents. </p>
<p>Furthermore, our regional study targeting the three continents where most kimberlites are found – Africa, South America and North America – supported this finding. It also added a major clue: kimberlite eruptions tend to gradually migrate from the continental edges to the interiors over time at a rate that is uniform across the continents.</p>
<p>This begs the question: what geological process could explain these patterns?
To address this question, we employed multiple computer models to capture the complex behaviour of continents as they experience stretching, alongside the convective movements within the underlying mantle.</p>
<h2>Domino effect</h2>
<p>We propose that a domino effect can explain how breakup of the continents eventually leads to formation of kimberlite magma. During <a href="https://egusphere.copernicus.org/preprints/2022/egusphere-2022-139/">rifting</a>, a small region of the continental root – areas of thick rock located under some continents – is disrupted and sinks into the underlying mantle. </p>
<p>Here, we get sinking of colder material and upwelling of hot mantle, causing a process called <a href="https://www.sciencedirect.com/science/article/abs/pii/S0012821X98000892">edge-driven convection</a>. Our models show that this convection triggers a chain of similar flow patterns that migrate beneath the nearby continent. </p>
<p>Our models show that while sweeping along the continental root, these disruptive flows remove a substantial amount of rock, tens of kilometres thick, from the base of the continental plate. </p>
<p>Various other results from our computer models then advance to show that this process can bring together the necessary ingredients in the right amounts to trigger just enough melting to generate gas-rich kimberlites. Once formed, and with great buoyancy provided by carbon dioxide and water, the magma can rise rapidly to the surface carrying its precious cargo. </p>
<figure class="align-center ">
<img alt="Eruption on western vent in Halema‘uma‘u crater, at the summit of Kīlauea." src="https://images.theconversation.com/files/539520/original/file-20230726-19-y5r0d0.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/539520/original/file-20230726-19-y5r0d0.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/539520/original/file-20230726-19-y5r0d0.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/539520/original/file-20230726-19-y5r0d0.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/539520/original/file-20230726-19-y5r0d0.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/539520/original/file-20230726-19-y5r0d0.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/539520/original/file-20230726-19-y5r0d0.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">It hasn’t been clear how the molten rock carrying diamonds got to the surface from deep within the Earth.</span>
<span class="attribution"><a class="source" href="https://www.usgs.gov/media/images/close-view-west-vent-halemaumau-kilauea-october-5-2021">N. Deligne / USGS</a></span>
</figcaption>
</figure>
<h2>Finding new diamond deposits</h2>
<p>This model doesn’t contradict the spatial association between kimberlites and mantle plumes. On the contrary, the breakup of tectonic plates may or may not result from the warming, thinning and weakening of the plate caused by plumes. </p>
<p>However, our research clearly shows that the spatial, time-based and chemical patterns observed in most kimberlite-rich regions can’t be adequately explained solely by the presence of plumes.</p>
<p>The processes triggering the eruptions that bring diamonds to the surface appear to be highly systematic. They start on the edges of continents and migrate towards the interior at a relatively uniform rate.</p>
<p>This information could be used to identify the possible locations and timings of past volcanic eruptions tied to this process, offering insights that could enable the discovery of diamond deposits and other rare elements needed for the green energy transition. </p>
<p>If we are to look for new deposits, it’s worth bearing in mind that there are currently efforts by campaign groups to try to eliminate from world markets those diamonds that are <a href="https://fpi.ec.europa.eu/what-we-do/kimberley-process-fight-against-conflict-diamonds_en">used to fund wars</a> (conflict diamonds) or those coming from mines with poor conditions for workers.</p>
<p>Diamonds may or may not be forever, but our work shows that new ones have been repeatedly created over long periods in the history of our planet.</p><img src="https://counter.theconversation.com/content/210421/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Thomas Gernon receives funding from the WoodNext Foundation and the Natural Environment Research Council (NERC). </span></em></p>Scientists were not previously certain how the precious stones arrived at the Earth’s surface.Thomas Gernon, Associate Professor in Earth Science, University of SouthamptonLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2070312023-07-05T20:05:49Z2023-07-05T20:05:49ZVolcano eruptions are notoriously hard to forecast. A new method using lasers could be the key<figure><img src="https://images.theconversation.com/files/534721/original/file-20230629-28-952crh.jpg?ixlib=rb-1.1.0&rect=105%2C169%2C4298%2C2738&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/etna-eruption-sicily-lava-nature-1560571136">Shutterstock</a></span></figcaption></figure><p>When you hear news reports about volcanoes spewing lava and ash, you may worry about the people nearby. In fact, almost one in ten people around the world <a href="https://www.cambridge.org/core/books/global-volcanic-hazards-and-risk/global-volcanic-hazard-and-risk/E0B20AB275CDB097BF802665DD6DA9A6">live within 100 kilometres of an active volcano</a>. For those living close to volcanoes, farming on their fertile soils, or visiting their spectacular landscapes, it is crucial to understand the drivers of eruption. </p>
<p>Why is the volcano erupting? How will the eruption evolve? When will it finish?</p>
<p>Our <a href="http://www.science.org/doi/10.1126/sciadv.adg4813">new research</a> published today in Science Advances applies laser technology to read into the chemical composition of erupted magma over time. </p>
<p>Because the chemistry of magmas affects their fluidity, explosivity and hazard potential, our work could help future monitoring and forecasting of the evolution of volcanic eruptions. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/why-cant-we-predict-when-a-volcano-will-erupt-53898">Why can't we predict when a volcano will erupt?</a>
</strong>
</em>
</p>
<hr>
<h2>Untangling the chemistry of erupted melt</h2>
<p>Magma – molten rock – is composed of liquid (known as “melt”), gas and crystals that grow as the temperature of the magma drops during its journey up to Earth’s surface.</p>
<p>When the magma erupts to become a lava flow, it will release the gas (which contains water vapour, carbon dioxide, sulphur dioxide and other compounds) and cool down into a volcanic rock. This rock contains crystals cooled slowly inside the volcano, embedded in a finer rock matrix cooled rapidly at the surface.</p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/534728/original/file-20230629-27-cuhqv4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A black background with colourful crystals in it" src="https://images.theconversation.com/files/534728/original/file-20230629-27-cuhqv4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/534728/original/file-20230629-27-cuhqv4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=962&fit=crop&dpr=1 600w, https://images.theconversation.com/files/534728/original/file-20230629-27-cuhqv4.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=962&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/534728/original/file-20230629-27-cuhqv4.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=962&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/534728/original/file-20230629-27-cuhqv4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1209&fit=crop&dpr=1 754w, https://images.theconversation.com/files/534728/original/file-20230629-27-cuhqv4.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1209&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/534728/original/file-20230629-27-cuhqv4.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1209&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Microscope view of lava erupted on October 24 2021 at La Palma, with large colourful crystals in a fine-grained black rock matrix which we analyse via laser. The image is in cross-polarised transmitted light (5mm scale bar).</span>
<span class="attribution"><span class="source">A. MacDonald</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>As a result, volcanic rocks can <a href="https://theconversation.com/there-she-blows-the-internal-magma-filter-that-prompts-ocean-island-volcanoes-to-erupt-167358">look a bit like “rocky road” chocolate</a>. The <a href="https://theconversation.com/volcano-crystals-could-make-it-easier-to-predict-eruptions-90558">crystals</a> formed in the guts of the volcano are excellent archives of the run-up to eruption. However, the crystals can get in the way when we want to focus on the melt that carries them to the surface, and how the melt properties vary throughout the eruption. </p>
<p>To isolate the melt signal, we used an ultraviolet laser, similar to the ones used for eye surgery, to blast the rock matrix between larger crystals.</p>
<p>We then analysed the laser-generated particles by <a href="https://www.britannica.com/science/mass-spectrometry">mass spectrometry</a> to determine the chemical composition of the volcanic matrix. The method allows for a rapid chemical analysis.</p>
<p>This provides a faster and more detailed measure of melt chemistry and its evolution over time, compared to traditional analysis of the entire rock, or to painstaking separation of matrix and crystal fragments from crushed rock samples. Even if we call the crystals “large”, they are often as small as a grain of salt (or up to a chickpea in size if you are lucky!) and difficult to remove. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/the-pulse-of-a-volcano-can-be-used-to-help-predict-its-next-eruption-117005">The 'pulse' of a volcano can be used to help predict its next eruption</a>
</strong>
</em>
</p>
<hr>
<h2>A destructive disaster in the Canary Islands</h2>
<p>Our study focused on the <a href="https://en.wikipedia.org/wiki/2021_Cumbre_Vieja_volcanic_eruption">2021 eruption at La Palma</a>, the most destructive volcanic eruption on historical record in the Canary Islands.</p>
<p>From September to December 2021, a total of 160 million cubic metres of lava covered more than 12 square kilometres of land. It destroyed more than 1,600 homes, forced the evacuation of more than 7,000 people and generated losses of more than <a href="https://ec.europa.eu/regional_policy/en/newsroom/news/2022/03/22-03-2022-eu-solidarity-eur5-4-million-of-advance-payments-to-spain-following-the-volcanic-eruption-in-la-palma">€860 million</a> (AU$1.4 billion). </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/534724/original/file-20230629-21-uph29m.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Aerial photo of houses with a river of lava flowing in between" src="https://images.theconversation.com/files/534724/original/file-20230629-21-uph29m.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/534724/original/file-20230629-21-uph29m.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/534724/original/file-20230629-21-uph29m.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/534724/original/file-20230629-21-uph29m.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/534724/original/file-20230629-21-uph29m.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=565&fit=crop&dpr=1 754w, https://images.theconversation.com/files/534724/original/file-20230629-21-uph29m.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=565&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/534724/original/file-20230629-21-uph29m.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=565&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Drone image of a lava flow from the 2021 La Palma eruption (December 4 2021, houses for scale).</span>
<span class="attribution"><span class="source">Instituto Geologico y Minero de Espana</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>We analysed lava samples collected systematically by our collaborators in Spain throughout the three months of eruption. These are precious samples as we know their exact eruption day, and many of the sampling sites are now covered by later lavas from the eruption. </p>
<p>Using the laser-powered method, we could see variations in lava chemistry linked to changes in earthquakes and sulphur dioxide emissions, as well as eruption style and the resulting hazards. This included a change from thick lavas that acted as a bulldozer at the start of the eruption, to runny lavas that created rapid <a href="https://twitter.com/i_ameztoy/status/1665062180713103362?s=20">lava rivers</a> and lava tunnels later in the eruption.</p>
<p>We also found a key change in lava chemistry about two weeks before the eruption ended, which suggests cooling of the magma due to a dropping magma supply.</p>
<p>Similar changes could be monitored as a signal of eruption wind-down in future eruptions around the world. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/534729/original/file-20230629-23-v10rmi.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/534729/original/file-20230629-23-v10rmi.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/534729/original/file-20230629-23-v10rmi.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/534729/original/file-20230629-23-v10rmi.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/534729/original/file-20230629-23-v10rmi.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/534729/original/file-20230629-23-v10rmi.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/534729/original/file-20230629-23-v10rmi.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/534729/original/file-20230629-23-v10rmi.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Early lavas from the 2021 La Palma eruption were voluminous and blocky, acting as a hot ‘bulldozer’ (September 22 2021, traffic sign for scale).</span>
<span class="attribution"><span class="source">JJ Coello Bravo</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<h2>Forecasting volcanic activity</h2>
<p>We cannot prevent volcanoes from erupting, and we cannot yet travel inside them <a href="https://en.wikipedia.org/wiki/Journey_to_the_Center_of_the_Earth">like French sci-fi author Jules Verne once envisioned</a>. But <a href="https://www.usgs.gov/programs/VHP/comprehensive-monitoring-provides-timely-warnings-volcano-reawakening">volcano monitoring</a> has improved enormously in the last few decades to allow us to indirectly ‘peek into’ volcanoes and better forecast their activity.</p>
<p>Our work aims to provide a laboratory tool for testing volcanic samples collected during future eruptions. The goal is to read into the evolution of eruptions, to understand why they start and when they will end. </p>
<p>With <a href="https://volcano.si.edu/">about 50 volcanoes erupting</a> at any given time around the world, you will soon see another volcano erupting in the news. This time, you can consider the importance of volcano science to improve our understanding of how volcanoes work and what drives them to erupt, to protect the people around them. </p>
<hr>
<p><em>Correction: an earlier version of this article stated the 2021 La Palma eruption released 160 cubic metres of lava. The correct figure is 160 million cubic metres.</em></p><img src="https://counter.theconversation.com/content/207031/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Teresa Ubide works for The University of Queensland. She receives funding from the Australian Research Council, AuScope-NCRIS, and The University of Queensland. </span></em></p><p class="fine-print"><em><span>Alice MacDonald is a PhD Student at The University of Queensland and receives a RTP PhD Stipend from UQ. </span></em></p><p class="fine-print"><em><span><a href="mailto:jack.mulder@adelaide.edu.au">jack.mulder@adelaide.edu.au</a> receives funding from the Australian Research Council, AuScope-NCRIS, The University of Adelaide. </span></em></p>One in ten people around the world live near an active volcano. Understanding the drivers of eruptions is crucial.Teresa Ubide, Associate Professor - Igneous Petrology/Volcanology, The University of QueenslandAlice MacDonald, PhD Student, The University of QueenslandJack Mulder, Lecturer, University of AdelaideLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2033922023-05-15T12:33:42Z2023-05-15T12:33:42ZWhy don’t rocks burn?<figure><img src="https://images.theconversation.com/files/523325/original/file-20230427-232-11japl.jpg?ixlib=rb-1.1.0&rect=44%2C0%2C5000%2C3308&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">The Jharia coal field in India has been on fire underground since 1916.</span> <span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/news-photo/in-the-village-liloripathra-that-is-located-on-the-top-of-news-photo/1227824345">Jonas Gratzer/LightRocket via Getty Images</a></span></figcaption></figure><figure class="align-left ">
<img alt="" src="https://images.theconversation.com/files/281719/original/file-20190628-76743-26slbc.png?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/281719/original/file-20190628-76743-26slbc.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=293&fit=crop&dpr=1 600w, https://images.theconversation.com/files/281719/original/file-20190628-76743-26slbc.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=293&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/281719/original/file-20190628-76743-26slbc.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=293&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/281719/original/file-20190628-76743-26slbc.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=368&fit=crop&dpr=1 754w, https://images.theconversation.com/files/281719/original/file-20190628-76743-26slbc.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=368&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/281719/original/file-20190628-76743-26slbc.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=368&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption"></span>
</figcaption>
</figure>
<p><em><a href="https://theconversation.com/us/topics/curious-kids-us-74795">Curious Kids</a> is a series for children of all ages. If you have a question you’d like an expert to answer, send it to <a href="mailto:curiouskidsus@theconversation.com">curiouskidsus@theconversation.com</a>.</em></p>
<hr>
<blockquote>
<p>Why don’t rocks burn? – Luke, age 4, New Market, New Hampshire</p>
</blockquote>
<hr>
<p>While many rocks don’t burn, some of them do. It depends on what the rocks are made of – and that’s related to how they were formed.</p>
<p>There are three main rock types: <a href="https://www.usgs.gov/faqs/what-are-igneous-rocks">igneous</a>, <a href="https://www.usgs.gov/faqs/what-are-sedimentary-rocks">sedimentary</a> and <a href="https://www.usgs.gov/faqs/what-are-metamorphic-rocks">metamorphic</a>. These rocks are made of minerals that all have different characteristics. Some will melt into <a href="https://www.usgs.gov/faqs/what-difference-between-magma-and-lava">magma or lava</a> – super-hot, liquid rock – when they are exposed to heat. Others will catch fire.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/7Bxw4kkeHJ8?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Rocks can look alike, but one rock is not like another.</span></figcaption>
</figure>
<p>Rocks that burn when they get heated up <a href="https://www.grc.nasa.gov/www/k-12/airplane/combst1.html">are combusting</a>. This means that elements within the rocks are reacting with oxygen in the air to produce heat and light, in the form of flames. </p>
<p>The elements <a href="https://www.rsc.org/periodic-table/element/16/sulfur">sulfur</a>, <a href="https://www.rsc.org/periodic-table/element/6/carbon">carbon</a> and <a href="https://www.rsc.org/periodic-table/element/1/hydrogen">hydrogen</a> easily react with oxygen. Rocks that contain these elements are combustible. Without these elements inside them, rocks that are exposed to enough heat will melt instead of catching fire.</p>
<h2>How rocks form</h2>
<p><a href="https://www.usgs.gov/faqs/what-are-igneous-rocks">Igneous rocks</a> are formed when magma underground or <a href="https://theconversation.com/curious-kids-how-can-we-tell-when-a-volcano-is-going-to-erupt-147703">lava from a volcano</a> cools and crystallizes into solid material. These rocks are mostly made of <a href="https://www.britannica.com/science/silicate-mineral">silicate minerals</a> that crystallize at temperatures from 1,300 degrees Fahrenheit (700 degrees Celsius) up to <a href="https://education.nationalgeographic.org/resource/magma-role-rock-cycle/">as high as 2,400 F (1,300 C)</a>.</p>
<p>Igneous rocks contain few or no combustible elements. And it’s very hard to remelt them back into magma because they crystallize at such high temperatures – it would take the kind of <a href="https://theconversation.com/why-cant-we-throw-all-our-trash-into-a-volcano-and-burn-it-up-170919">high-tech incinerator that cities use to burn waste</a> to make that happen.</p>
<p><a href="https://www.usgs.gov/faqs/what-are-sedimentary-rocks">Sedimentary rocks</a> have a very different formation story. They form from broken bits of rocks, minerals, sometimes plant or animal material, and also crystals left behind when water evaporates, like the <a href="https://www.compoundchem.com/2016/03/02/limescale/">limescale</a> that forms in teakettles and bathtubs. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/523326/original/file-20230427-14-w7d3zk.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Infographic showing materials washing into the ocean and becoming compressed at depth." src="https://images.theconversation.com/files/523326/original/file-20230427-14-w7d3zk.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/523326/original/file-20230427-14-w7d3zk.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=423&fit=crop&dpr=1 600w, https://images.theconversation.com/files/523326/original/file-20230427-14-w7d3zk.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=423&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/523326/original/file-20230427-14-w7d3zk.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=423&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/523326/original/file-20230427-14-w7d3zk.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=531&fit=crop&dpr=1 754w, https://images.theconversation.com/files/523326/original/file-20230427-14-w7d3zk.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=531&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/523326/original/file-20230427-14-w7d3zk.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=531&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Sedimentary rock forms when layers of material are compressed over time, either on land or under water.</span>
<span class="attribution"><a class="source" href="https://flic.kr/p/mGbBa2">Siyavula Education/Flickr</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<p>There is a lot of <a href="https://www.rsc.org/periodic-table/element/16/sulfur">sulfur</a>, <a href="https://www.rsc.org/periodic-table/element/6/carbon">carbon</a> and <a href="https://www.rsc.org/periodic-table/element/1/hydrogen">hydrogen</a> in living things. In fact, these are three of the <a href="https://www.livescience.com/32983-what-are-ingredients-life.html">six essential elements of life on Earth</a>. Bits of organic matter, particularly dead plants, also are combustible and allow the rocks to burn. </p>
<p>The last group of rocks is called <a href="https://www.usgs.gov/faqs/what-are-metamorphic-rocks">metamorphic</a>, because these rocks form when a lot of heat and pressure change existing rocks into new types without melting or burning them. “Metamorphosis” comes from ancient Greek and means “transformation.” For example, marble that you might see in kitchen counters or statues came from limestone that was transformed under intense heat and pressure deep underground. </p>
<h2>The rock that humans burn: Coal</h2>
<p>Metamorphic rocks that are formed from igneous rocks won’t contain the combustible elements – the ones that burn – but metamorphic rocks made from sedimentary rocks might. One familiar example is <a href="https://www.usgs.gov/faqs/what-are-types-coal">anthracite coal</a>, which is made almost entirely of carbon. It formed when dead plants fell into swamps long, long ago, were buried by sand or mud, and eventually were compressed over <a href="https://eartharchives.org/articles/the-evolution-of-plants-part-3-the-age-of-coal/index.html">hundreds of millions of years into coal</a>. </p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/523327/original/file-20230427-2850-2212o2.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A large chunk of anthracite coal." src="https://images.theconversation.com/files/523327/original/file-20230427-2850-2212o2.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/523327/original/file-20230427-2850-2212o2.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=901&fit=crop&dpr=1 600w, https://images.theconversation.com/files/523327/original/file-20230427-2850-2212o2.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=901&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/523327/original/file-20230427-2850-2212o2.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=901&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/523327/original/file-20230427-2850-2212o2.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1132&fit=crop&dpr=1 754w, https://images.theconversation.com/files/523327/original/file-20230427-2850-2212o2.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1132&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/523327/original/file-20230427-2850-2212o2.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1132&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Anthracite is the hardest type of coal. It contains the most carbon and the fewest impurities of all coal types.</span>
<span class="attribution"><a class="source" href="https://en.wikipedia.org/wiki/Anthracite#/media/File:Anthracite_chunk.JPG">Jakec/Wikipedia</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
</figcaption>
</figure>
<p>There are many coal seams around the world. Sometimes the coal even <a href="https://www.smithsonianmag.com/science-nature/fire-in-the-hole-77895126/">catches fire while it’s still in the ground</a>. The cause can be natural, such as a lightning strike, or human activities like mining.</p>
<p>In Centralia, Pennsylvania, a former mining town, a coal seam has been <a href="https://www.smithsonianmag.com/science-nature/fire-in-the-hole-77895126/">burning for over 50 years</a>. There are other active coal seam fires in places around the world including <a href="https://eos.org/articles/coal-seam-fires-burn-beneath-communities-in-zimbabwe">Zimbabwe in Africa</a> and <a href="https://www.cnbc.com/2015/12/02/indias-jharia-coal-field-has-been-burning-for-100-years.html">Jharia in India</a>.</p>
<p>If carbon is compressed with even more pressure than it takes to make coal, eventually <a href="https://theconversation.com/diamonds-are-forever-whether-made-in-a-lab-or-mined-from-the-earth-106665">you get diamonds</a> – the <a href="https://theconversation.com/have-scientists-really-found-something-harder-than-diamond-52391">hardest mineral found in nature</a>. In 1772, French chemist <a href="https://www.britannica.com/biography/Antoine-Lavoisier">Antoine Lavoisier</a> proved that diamonds could combust when he <a href="https://www.wtamu.edu/%7Ecbaird/sq/2014/03/27/can-you-light-diamond-on-fire/">burned one with a magnifying glass</a>. </p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/1QbHRLpYc-0?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Scientists burn a diamond – the hardest mineral found in nature.</span></figcaption>
</figure>
<p>With enough patience, you could <a href="https://www.wtamu.edu/%7Ecbaird/sq/2014/03/27/can-you-light-diamond-on-fire/">burn a diamond in a candle flame</a>. But since diamonds are quite expensive, it’s better to stick to <a href="https://gosciencegirls.com/magnifying-glass-fire/">burning other things made of carbon</a>, like <a href="https://gosciencekids.com/magnifying-glass-fire/">leaves under a magnifying glass</a>, or sticks and marshmallows in a campfire, instead. </p>
<hr>
<p><em>Hello, curious kids! Do you have a question you’d like an expert to answer? Ask an adult to send your question to <a href="mailto:curiouskidsus@theconversation.com">CuriousKidsUS@theconversation.com</a>. Please tell us your name, age and the city where you live.</em></p>
<p><em>And since curiosity has no age limit – adults, let us know what you’re wondering, too. We won’t be able to answer every question, but we will do our best.</em></p><img src="https://counter.theconversation.com/content/203392/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Natalie Bursztyn does not work for, consult, own shares in or receive funding from any company or organization that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>Some rocks will burn, and others will melt, depending on how they were formed and what minerals they contain.Natalie Bursztyn, Lecturer in Geosciences, University of MontanaLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1957042023-05-01T12:10:20Z2023-05-01T12:10:20ZWhat causes volcanoes to erupt?<figure><img src="https://images.theconversation.com/files/501671/original/file-20221218-11129-2abr3x.jpg?ixlib=rb-1.1.0&rect=7%2C0%2C4985%2C3323&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">An aerial view of the Mauna Loa volcano, which erupted on the island of Hawaii in December 2022.</span> <span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/news-photo/in-an-aerial-view-lava-erupts-from-the-mauna-loa-volcano-on-news-photo/1245459430?phrase=Mauna%20Loa%20volcano%202022&adppopup=true">Andrew Richard Hara/Getty Images News</a></span></figcaption></figure><figure class="align-left ">
<img alt="" src="https://images.theconversation.com/files/281719/original/file-20190628-76743-26slbc.png?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/281719/original/file-20190628-76743-26slbc.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=293&fit=crop&dpr=1 600w, https://images.theconversation.com/files/281719/original/file-20190628-76743-26slbc.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=293&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/281719/original/file-20190628-76743-26slbc.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=293&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/281719/original/file-20190628-76743-26slbc.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=368&fit=crop&dpr=1 754w, https://images.theconversation.com/files/281719/original/file-20190628-76743-26slbc.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=368&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/281719/original/file-20190628-76743-26slbc.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=368&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption"></span>
</figcaption>
</figure>
<p><em><a href="https://theconversation.com/us/topics/curious-kids-us-74795">Curious Kids</a> is a series for children of all ages. If you have a question you’d like an expert to answer, send it to <a href="mailto:curiouskidsus@theconversation.com">curiouskidsus@theconversation.com</a>.</em></p>
<hr>
<blockquote>
<p><strong>What causes volcanoes to erupt? – Avery, age 8, Los Angeles</strong></p>
</blockquote>
<hr>
<p>On Nov. 27, 2022, Mauna Loa – the world’s largest active volcano – <a href="https://www.usgs.gov/observatories/hvo/news/volcano-watch-mauna-loa-reawakens-0">erupted on the island of Hawaii</a>. For days, fountains of lava, boiling at more than 2,000 degrees Fahrenheit (1,100 degrees Celsius), spewed upward and flowed down the mountain’s sides. </p>
<p>For tens of millions of people around the world, the videos were a mesmerizing sight. Then, a few weeks later, the eruption ended. Fortunately, there were no known deaths, and no major property damage. </p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/F0tmu-zaXig?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Mauna Loa is the world’s largest active volcano.</span></figcaption>
</figure>
<p>About a week later, Mount Semeru in East Java, Indonesia, <a href="https://volcano.si.edu/volcano.cfm?vn=263300">erupted a mix of ash, gas and hot rocks</a>. The plumes rose a mile above the mountain’s summit. Thousands <a href="https://www.pbs.org/newshour/world/new-eruption-of-indonesias-mt-semeru-unleashes-lava-river-volcanic-ash">living in the vicinity were evacuated</a>; many wore masks to protect themselves from the ash-filled air. Mount Semeru has continued to erupt for months.</p>
<p>I am a geologist who <a href="https://scholar.google.com/citations?user=4Q8uMqUAAAAJ&hl=en&oi=ao">studies minerals in volcanic rocks</a>. I want to learn more about what causes volcanoes to erupt. Millions of people <a href="https://www.discovery.com/exploration/People-Live-Near-Active-Volcanoes">live near an active volcano</a> – that is, one of the 1,328 volcanoes worldwide that have <a href="https://volcano.si.edu/faq/index.cfm?question=activevolcanoes">erupted over the past 12,000 years</a>. </p>
<p>At any given time, 20 to 50 of these <a href="https://volcano.si.edu/gvp_currenteruptions.cfm">active volcanoes are erupting</a>. The proximity of people and buildings makes it important to study volcanoes and understand the hazards. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/502804/original/file-20230102-22-tpygfq.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A photograph of the city of Naples, Italy, with Mount Vesuvius in the background." src="https://images.theconversation.com/files/502804/original/file-20230102-22-tpygfq.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/502804/original/file-20230102-22-tpygfq.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=370&fit=crop&dpr=1 600w, https://images.theconversation.com/files/502804/original/file-20230102-22-tpygfq.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=370&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/502804/original/file-20230102-22-tpygfq.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=370&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/502804/original/file-20230102-22-tpygfq.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=465&fit=crop&dpr=1 754w, https://images.theconversation.com/files/502804/original/file-20230102-22-tpygfq.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=465&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/502804/original/file-20230102-22-tpygfq.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=465&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Mount Vesuvius, about 6 miles east of Naples, Italy, is still an active volcano. In A.D. 79, Vesuvius erupted and destroyed the city of Pompeii.</span>
<span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/photo/travelling-in-italy-royalty-free-image/906204248?phrase=volcanoes%20mount%20vesuvius&adppopup=true">Antonio Busiello/Moment via Getty Images</a></span>
</figcaption>
</figure>
<h2>How volcanoes blow their stacks</h2>
<p>The center of the Earth is <a href="https://earthhow.com/inside-earth-crust-core-mantle/">called the core</a>; the next layer up is the mantle; the outermost layer is the crust. </p>
<p>Over time, <a href="https://kids.kiddle.co/Magma">magma</a> – which is melted rock mixed with gas and mineral crystals – accumulates in an underground chamber beneath the volcano. The magma at Mauna Loa forms when a <a href="https://www.cbsnews.com/news/where-does-mauna-loa-lava-come-from/">hot mantle plume</a> – think of a conveyor of heat – partly melts rock in the mantle. </p>
<p>The volcano is essentially an <a href="https://www.natgeokids.com/uk/discover/geography/physical-geography/volcano-facts/">opening that lets magma out</a> onto the surface of the Earth. Once released from the volcano, the magma is called lava. </p>
<p>In the months leading to its eruption, scientists noted <a href="https://www.usgs.gov/observatories/hvo">increased earthquakes and a bulging of Mauna Loa</a>, like a balloon being inflated. These signs suggested that more magma was making its way upward, because pressure from rising magma can expand the sides of a volcano and cause rocks to shift and break, which leads to earthquakes.</p>
<p>Typically, for an eruption to occur, enough magma must <a href="https://www.usgs.gov/programs/VHP/about-volcanoes">accumulate in the chamber under the volcano</a>. Then something needs to trigger the eruption. That could be an injection of new magma into the chamber, a buildup of gases within the volcano, or a landslide that removes material from the top of a volcano.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/XLF_lMY2gu8?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">The eruption on Mount Semeru forced an evacuation of nearly 2,000 nearby residents.</span></figcaption>
</figure>
<h2>Types of volcanoes</h2>
<p>Mauna Loa is a <a href="https://study.com/academy/lesson/shield-volcano-facts-lesson-for-kids.html#:%7E">shield volcano</a>, built up over thousands of years through lava eruptions. Its sides slope gently downward in all directions. </p>
<p>But Mount Semeru is different – it’s a <a href="https://study.com/academy/lesson/composite-volcano-facts-lesson-for-kids.html#:%7E">composite volcano</a>, also known as a stratovolcano, with steep sides that come to a point at the top, like an upside-down sugar cone. </p>
<p>Semeru’s most recent eruption started when heavy rains <a href="https://www.cnn.com/2021/12/08/asia/indonesia-mount-semeru-volcano-eruption-cimate-intl/index.html">washed away rocks near the top of the volcano</a>. That allowed gas to escape – and ash to start erupting. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/517451/original/file-20230324-24-crlmkn.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A motorbike, and the ground around it, covered in ash." src="https://images.theconversation.com/files/517451/original/file-20230324-24-crlmkn.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/517451/original/file-20230324-24-crlmkn.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/517451/original/file-20230324-24-crlmkn.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/517451/original/file-20230324-24-crlmkn.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/517451/original/file-20230324-24-crlmkn.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/517451/original/file-20230324-24-crlmkn.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/517451/original/file-20230324-24-crlmkn.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">After the eruption at Mount Semeru, nearby villages were covered in volcanic ash.</span>
<span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/news-photo/motorbike-is-covered-with-volcanic-ashes-after-mount-semeru-news-photo/1237024024?adppopup=true">Bayu Novanta/Xinhua News Agency via Getty Images</a></span>
</figcaption>
</figure>
<h2>The dangers</h2>
<p>Many hazards are associated with erupting volcanoes: lava flows, acidic gases, ash and <a href="https://www.usgs.gov/observatories/cascades-volcano-observatory/lahars-most-threatening-volcanic-hazard-cascades#:%7E">lahars</a>, which are dangerous flows of water, ash and rock that <a href="https://www.usgs.gov/programs/VHP/lahars-move-rapidly-down-valleys-rivers-concrete">run miles down the steep slopes of volcanoes</a>, sometimes <a href="https://www.usgs.gov/programs/VHP/lahars-move-rapidly-down-valleys-rivers-concrete#:%7E">at over 100 miles per hour</a>. The force of lahars can move huge boulders and destroy bridges and buildings. </p>
<p>Mount Semeru’s recent eruption <a href="https://www.usgs.gov/programs/VHP/ashfall-most-widespread-and-frequent-volcanic-hazard">covered nearby villages with ash</a> – tiny particles of rock that can go deep into lungs, causing irritation and making it hard to breathe. </p>
<p>As falling ash accumulates, it can smother crops, contaminate water supplies and trigger the collapse of buildings. Newly fallen dry ash weighs <a href="https://mil.wa.gov/asset/5ba4200a0b533#:%7E:text=Ash%20accumulates%20like%20heavy%20snowfall,Wet%20ash%20is%20slippery.">10 to 20 times more than snow</a>. </p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/3Jxeh-yAXek?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Below the surface, Earth is always moving and changing.</span></figcaption>
</figure>
<p>Generally, scientists don’t try to stop volcanoes from erupting. They are a natural part of the Earth. But monitoring volcanoes is critical. People need an early warning of an eruption <a href="https://www.usgs.gov/programs/VHP/understanding-volcanic-hazards-can-save-lives">so they can move out of harm’s way</a>. </p>
<p>While we cannot predict the exact time of an eruption, scientists are learning more about what causes them, and how to protect people who live near them. </p>
<p>What’s critical: warning systems for lahars, planned evacuation routes in areas threatened by volcanoes, and excellent communication between the scientists at volcanic monitoring stations and government agencies who can let people know when a volcano is about to go. </p>
<hr>
<p><em>Hello, curious kids! Do you have a question you’d like an expert to answer? Ask an adult to send your question to <a href="mailto:curiouskidsus@theconversation.com">CuriousKidsUS@theconversation.com</a>. Please tell us your name, age and the city where you live.</em></p>
<p><em>And since curiosity has no age limit – adults, let us know what you’re wondering, too. We won’t be able to answer every question, but we will do our best.</em></p><img src="https://counter.theconversation.com/content/195704/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Rachel Beane receives funding from Bowdoin College and the National Science Foundation. She is affiliated with the Harpswell Heritage Land Trust. </span></em></p>As they shape the Earth, volcanoes inspire and terrify humans.Rachel Beane, Professor of Natural Sciences, Bowdoin CollegeLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1957032022-12-06T13:34:43Z2022-12-06T13:34:43ZNative Hawaiians believe volcanoes are alive and should be treated like people, with distinct rights and responsibilities<figure><img src="https://images.theconversation.com/files/499069/original/file-20221205-22-ww08xg.jpg?ixlib=rb-1.1.0&rect=57%2C8%2C5398%2C3612&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Hawaii's Mauna Loa's volcano is erupting for the first time in nearly 40 years.</span> <span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/news-photo/people-gather-on-top-of-a-hill-to-watch-mauna-loa-erupts-news-photo/1245294420?phrase=mauna%20loa&adppopup=true">Tayfun Coskun/Anadolu Agency via Getty Images</a></span></figcaption></figure><p>Hawaii’s largest and oldest volcano, <a href="https://www.usgs.gov/news/featured-story/mauna-loa-has-begun-erupting">Mauna Loa, began erupting</a> on Nov. 27, 2022, with lava flowing miles away downhill. The last eruption, which lasted three weeks, <a href="https://www.khon2.com/local-news/mauna-loa-eruption/last-mauna-loa-eruption-was-nearly-40-years-ago/">was nearly 40 years ago</a>. </p>
<p>It is not clear how long this eruption will last, but for many Native Hawaiians, <a href="https://www.cnn.com/videos/us/2022/12/04/hawaii-mauna-loa-volcano-eruption-culture-pele-ilihia-gionson-intv-whitfield-nrtf.cnn">it is a profound spiritual experience</a>. </p>
<p>As an <a href="https://ais.arizona.edu/users/richard-stoffle">anthropologist</a>, I have conducted <a href="https://doi.org/10.3390/land11020196">nine studies</a> on traditional Native American cultural relationships with volcanic lava flows. As in most Native American cultures, <a href="https://www.researchgate.net/profile/Alex-Ruuska/publication/289537668_Ethnology_of_Volcanoes_Quali-Signs_and_the_Cultural_Centrality_of_Self-Voiced_Places/links/568fd8f608aecd716aedc011/Ethnology-of-Volcanoes-Quali-Signs-and-the-Cultural-Centrality-of-Self-Voiced-Places.pdf">Native Hawaiians’ beliefs hold</a> that Mauna Loa and other volcanoes are alive, and their eruptions are how the Earth is reborn. The volcano is like the Earth’s mother.</p>
<p>Since the volcano is alive, <a href="https://www.researchgate.net/publication/313558717_Talking_With_Nature_Southern_Paiute_Epistemology_and_The_Double_Hermeneutic_with_a_Living_Planet">it must be treated like a person</a> with rights and responsibilities and differently than if it were just flowing hot magma.
Not just the volcano – all elements of the Earth <a href="https://experts.arizona.edu/en/publications/living-universe-or-geofacts-stone-arches-in-utah-national-parks-e">are perceived as being alive</a>, with feelings, the ability to speak and the power to do things they wish.</p>
<p>This view of the living Earth defines as alive the plants that grow on the volcano, the wind that passes over it, the birds that nest near it, the water that flows from it after rains and the oceans it touches. </p>
<h2>The power of volcanoes</h2>
<p>Native Hawaiians maintain that since the Earth’s creation, volcanoes’ elements – earth, wind and fire – <a href="https://experts.arizona.edu/en/publications/living-universe-or-geofacts-stone-arches-in-utah-national-parks-e">have talked</a>. They believe that these elements have humanlike rights, such as to be heard and to have goals. Crystals, obsidian, basalt boulders and other products of volcanic activity each are alive, and all have roles in the lives of humans.</p>
<p>Interactions between the earth elements, the volcano and humans are perceived as continuous because living natural elements change and <a href="https://doi.org/10.3390/land11020196">thus need to adapt</a> to new conditions together with each other and people.</p>
<p>Native American scholar and spokesperson <a href="https://blogs.loc.gov/law/2016/11/remembering-vine-deloria-jr/">Vine Deloria Jr.</a> convened a Native Science of Volcanoes meeting in Albuquerque, New Mexico, in 2005. Among those who attended the meeting were this author and Native people from Washington state, Oregon, California, Arizona, Utah, Nevada and Hawaii, including elders from the Shoshone Bannock, Yakama, Owens Valley Paiute, Southern Paiute, Hopi, Nisqually, Winnemen-Wintu, Navajo and Klamath tribes.</p>
<p>These speakers said they regarded the volcanoes as living beings who, under certain circumstances, would share power and knowledge with humans. According to these elders, the volcano is a place where ceremonies are performed. The ceremonies are both an act of respect and a request for guidance. </p>
<p>Indigenous people believe their welfare and the Earth’s ecological balance are dependent on their continued and appropriate interactions with this living being.</p>
<h2>Pilgrimage and rituals</h2>
<p>Over tens of thousands of years, Native people have traveled to communicate with the same volcanoes during ceremonies. People traveled known physical and spiritual trails during these journeys. </p>
<p>Evidence shows that when pilgrims arrived at a destination volcano, they embedded the landscape with rock peckings, paintings, stone cairns, shrines, incised stones and many offerings. They sang and <a href="https://www.semanticscholar.org/paper/Puha-Po-to-Kavaicuwac%3A-a-Southern-Paiute-Pilgrimage-Vlack/fdd762ac2eb461a5c8e6d143df37e3197608d6c0">documented their relationship</a> with the volcano. </p>
<p>During the mid-11th century lava flows at Sunset Crater, Arizona, and Little Spring, Arizona, people <a href="https://doi.org/10.1007/978-3-030-78040-1_2">placed corn and painted pots</a> on the edge of hornitos – conical structures produced by bubbling lava. When new lava splashes occurred, the resulting stones were embedded with corn imprints and pot shards. These were knocked off the edge before they could cool. The rocks were then taken to a nearby location and became a part of the walls of a ceremonial structure. </p>
<h2>Management policies</h2>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/499070/original/file-20221205-20-sjtgq6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A map of Hawaii showing the location of Mauna Loa." src="https://images.theconversation.com/files/499070/original/file-20221205-20-sjtgq6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/499070/original/file-20221205-20-sjtgq6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=399&fit=crop&dpr=1 600w, https://images.theconversation.com/files/499070/original/file-20221205-20-sjtgq6.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=399&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/499070/original/file-20221205-20-sjtgq6.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=399&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/499070/original/file-20221205-20-sjtgq6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=501&fit=crop&dpr=1 754w, https://images.theconversation.com/files/499070/original/file-20221205-20-sjtgq6.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=501&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/499070/original/file-20221205-20-sjtgq6.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=501&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The eruptions of Mauna Loa raise the question of whether the volcano is a living being or inert.</span>
<span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/photo/hawaii-royalty-free-image/121043074?phrase=mauna%20loa&adppopup=true">KeithBinns/Collections E+ via Getty Images</a></span>
</figcaption>
</figure>
<p>Studies involving Native tribes and U.S. federal agencies have documented that the living Earth belief is <a href="https://fulcrum.bookstore.ipgbook.com/red-earth--white-lies-products-9781555913885.php">broadly shared in North America and Hawaii</a>. But Native peoples and their beliefs have not often been involved in land management policies and interpretations. </p>
<p>This, as I understand, is because of three main reasons: First, over the centuries, many Western scientists have believed that only they possess accurate knowledge about natural processes. Second, federal and state land managers have been given the legal responsibility to properly manage their parks and are reluctant to share power. And lastly, land managers don’t have the cultural knowledge to understand Native American beliefs or how to communicate with volcanoes. </p>
<p>Native people believe their ceremonial interactions with volcanoes result in the shared knowledge, which <a href="https://www.doi.org/10.1007/978-3-030-78040-1">some call Native Science</a>. They believe that volcanoes express ideas during ceremonies about how to keep themselves, the people and the world in balance. People can take this communication and act on it. But when Native beliefs are not perceived as science and thus not seen to be true or useful for management or interpretations, it creates what is known as an “<a href="https://www.doi.org/10.1007/978-3-030-78040-1">epistemological divide</a>. This hampers cross-cultural communication. </p>
<p>The eruptions of Mauna Loa are once again raising important questions about whether the volcano is a living being or inert. They also prompt questions about whether the eruption is for the benefit of humans or simply a threatening geological event that has no purpose. </p>
<p>The answer to these questions will influence how the volcano will be interpreted in the future for visitors and managed by geologists and environments.</p><img src="https://counter.theconversation.com/content/195703/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Richard W Stoffle receives funding from various federal organizations. </span></em></p>The eruption of Mauna Loa is a profound spiritual experience for many Native Hawaiians. An anthropologist explains Native American beliefs on the living Earth and volcanic lava.Richard W Stoffle, Professor of Anthropology, University of ArizonaLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1956332022-11-30T13:44:16Z2022-11-30T13:44:16ZWhere Mauna Loa’s lava is coming from – and why Hawaii’s volcanoes are different from most<figure><img src="https://images.theconversation.com/files/498437/original/file-20221201-6346-syova6.jpeg?ixlib=rb-1.1.0&rect=2568%2C1769%2C2083%2C1338&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Magma fountains through a fissure on Mauna Loa, becoming lava, on Nov. 30, 2022.
</span> <span class="attribution"><a class="source" href="https://www.usgs.gov/media/images/november-30-2022-mauna-loa-fissure-3"> K. Mulliken/USGS</a></span></figcaption></figure><p><em>Hawaii’s Mauna Loa, the world’s largest active volcano, began sending up <a href="https://www.usgs.gov/volcanoes/mauna-loa/mauna-loa-eruption-webpage">fountains of glowing rock</a> and spilling lava from fissures as its first eruption in <a href="https://www.usgs.gov/volcanoes/mauna-loa">nearly four decades</a> began on Nov. 27, 2022.</em> </p>
<p><em>Where does that molten rock come from?</em></p>
<p><em>We asked <a href="https://scholar.google.com/citations?user=a7D-WawAAAAJ&hl=en">Gabi Laske</a>, a geophysicist at the University of California-San Diego who led one of the first projects to map the deep plumbing that feeds the Hawaiian Islands’ volcanoes, to explain.</em> </p>
<h2>Where is the magma surfacing at Mauna Loa coming from?</h2>
<p>The magma that comes out of Mauna Loa comes from a series of magma chambers found between about 1 and 25 miles (2 and 40 km) below the surface. These magma chambers are only temporary storage places with magma and gases, and are not where the magma originally came from.</p>
<p>The origin is much deeper in <a href="https://pubs.usgs.gov/gip/dynamic/inside.html">Earth’s mantle</a>, perhaps more than 620 miles (1,000 km) deep. Some scientists even postulate that the magma comes from a <a href="https://www.usgs.gov/observatories/hvo/news/volcano-watch-exploring-deep-source-hawaiian-volcanoes">depth of 1,800 miles (2,900 km)</a>, where the mantle meets Earth’s core.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/498078/original/file-20221129-14-85b5yv.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/498078/original/file-20221129-14-85b5yv.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/498078/original/file-20221129-14-85b5yv.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=318&fit=crop&dpr=1 600w, https://images.theconversation.com/files/498078/original/file-20221129-14-85b5yv.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=318&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/498078/original/file-20221129-14-85b5yv.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=318&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/498078/original/file-20221129-14-85b5yv.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=400&fit=crop&dpr=1 754w, https://images.theconversation.com/files/498078/original/file-20221129-14-85b5yv.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=400&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/498078/original/file-20221129-14-85b5yv.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=400&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">An illustration suggests what Hawaii’s mantle plume might look like.</span>
<span class="attribution"><span class="source">Joel E Robinson/USGS</span></span>
</figcaption>
</figure>
<p>Earth’s crust is made up of tectonic plates that are slowly moving, at about the same speed as a fingernail grows. Volcanoes typically occur where these plates either move away from each other or where one pushes beneath another. But volcanoes can also be in the middle of plates, as Hawaii’s volcanoes are <a href="https://www.usgs.gov/media/images/pacific-plate-boundaries-and-relative-motion">in the Pacific Plate</a>.</p>
<p>The crust and mantle that comprise the Pacific Plate cracks at different places as it moves northwestward. Beneath Hawaii, magma can move upward through the cracks to feed different volcanoes on the surface. The same thing happens at Maui’s Haleakala, <a href="https://www.usgs.gov/volcanoes/haleakal%C4%81">which last erupted</a> about 250 years ago.</p>
<h2>How does molten rock travel from deep in Earth’s mantle, and what exactly is a mantle plume?</h2>
<p>Scientists hypothesize that the mantle is not made of uniform rock. Instead, <a href="https://doi.org/10.1038/s41561-019-0368-9">differences in the type</a> of mantle rock make it melt at <a href="https://openoregon.pressbooks.pub/earthscience/chapter/4-1-magma-and-how-it-forms/">different temperatures</a>. Mantle rock is solid at some places, while it starts to melt at other places.</p>
<p>The partially molten rock becomes buoyant and ascends toward the surface. The ascending mantle rock is what makes a mantle plume. Because the overlying pressure lessens as the rock ascends, it melts more and more, and eventually collects in the magma chamber. If a large enough opening exists at the surface, and enough volcanic gases have collected in the magma chamber, the magma is forced to the surface in a volcanic eruption.</p>
<figure class="align-center ">
<img alt="A cross section of the earth shows two potentially sources for the mantle plume, one starting much deeper and flowing a squiggly route as seismic imaging suggests." src="https://images.theconversation.com/files/498109/original/file-20221129-20-2d4cyv.gif?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/498109/original/file-20221129-20-2d4cyv.gif?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=398&fit=crop&dpr=1 600w, https://images.theconversation.com/files/498109/original/file-20221129-20-2d4cyv.gif?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=398&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/498109/original/file-20221129-20-2d4cyv.gif?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=398&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/498109/original/file-20221129-20-2d4cyv.gif?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=500&fit=crop&dpr=1 754w, https://images.theconversation.com/files/498109/original/file-20221129-20-2d4cyv.gif?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=500&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/498109/original/file-20221129-20-2d4cyv.gif?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=500&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">The origin of the magma may be more than 620 miles deep, and some scientists have suggested it could come from a depth of 1,800 miles, where the mantle meets Earth’s core.</span>
<span class="attribution"><span class="source">Gabi Laske</span></span>
</figcaption>
</figure>
<p>Seismic imaging by research teams I’m involved with has shown that Hawaii’s mantle plume <a href="https://doi.org/10.1126/science.1180165">comes from deep inside the mantle</a>.</p>
<p>But the plume is not a straight pipe as some concept figures suggest. Instead, it has <a href="https://doi.org/10.1038/ngeo1878">twists and turns</a>, originally coming from the southeast, but then turning toward the west of Hawaii as the plume reaches into the shallower mantle. Cracks in the Pacific Plate then channel the magma upward toward the magma chamber beneath the island of Hawaii.</p>
<h2>Why does Hawaii typically see less dramatic eruptions than other locations?</h2>
<p>Hawaii is in the middle of an oceanic plate. In fact, it is the most isolated volcanic hot spot on Earth, far away from any plate boundary.</p>
<p>Oceanic magma is very different from continental magma. It has a different chemical composition and flows much more easily. So, the magma is <a href="https://geowiki.ucsd.edu/sio15/topics/topic09.html">less prone to clog volcanic vents</a> on its ascent, which would ultimately lead to more explosive volcanism.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/9DUexRQfNBA?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Thermal imaging shows the Mauna Loa eruption, which began around 11:30 p.m. local time on Nov. 27, 2022. Temperatures are in Celsius. USGS.</span></figcaption>
</figure>
<h2>How do scientists know what is happening under the surface?</h2>
<p>Volcanic activity is monitored with many different instruments.</p>
<p>The perhaps simplest to understand is GPS. The way scientists use GPS is different from that of everyday life. It can detect minuscule movements of a few centimeters. On volcanoes, any upward movement on the surface detected by GPS indicates that something is pushing from underneath.</p>
<p>Even more sensitive are <a href="https://www.usgs.gov/programs/VHP/tiltmeters-and-strainmeters-measure-subtle-changes-ground-slope-and-shape-volcanoes">tiltmeters</a>, which are in essence the same as bubble levels that people use to hang pictures on a wall. Any change in the tilt on a volcano slope indicates that the volcano is “breathing,” again because of magma moving below.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/498080/original/file-20221129-14-pr28xg.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Map of the island of Hawaii, showing Mauna Loa and the lava flow paths since the late 1800s. There have been several eruptions and they tend to follow two routes." src="https://images.theconversation.com/files/498080/original/file-20221129-14-pr28xg.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/498080/original/file-20221129-14-pr28xg.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=776&fit=crop&dpr=1 600w, https://images.theconversation.com/files/498080/original/file-20221129-14-pr28xg.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=776&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/498080/original/file-20221129-14-pr28xg.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=776&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/498080/original/file-20221129-14-pr28xg.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=976&fit=crop&dpr=1 754w, https://images.theconversation.com/files/498080/original/file-20221129-14-pr28xg.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=976&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/498080/original/file-20221129-14-pr28xg.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=976&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Mauna Loa has a history of eruptions. Here’s where the lava tends to go.</span>
<span class="attribution"><a class="source" href="https://www.usgs.gov/volcanoes/mauna-loa/geology-and-history">USGS</a></span>
</figcaption>
</figure>
<p>A very important tool is watching for seismic activity.</p>
<p>Volcanoes like Hawaii’s are monitored with a large network of seismographs. Any movement of magma below will cause tremors that are picked up by the <a href="https://www.usgs.gov/programs/VHP/networks-multiple-seismometers-are-necessary-adequately-monitor-volcanoes">seismometers</a>. A few weeks before the eruption of Mauna Loa, scientists noticed that the tremors came from ever shallower depths, indicating that magma was rising and an eruption might be imminent. This <a href="https://apnews.com/article/science-hawaii-kilauea-mauna-loa-14f7596e22b08a44600caa5f185b5b18">allowed scientists to warn the public</a>.</p>
<p>Other ways that volcanic activity is monitored includes chemical analysis of gases coming out <a href="https://www.usgs.gov/news/earthword-fumarole">through fumaroles</a> – holes or cracks through which volcanic gases escape. If the composition changes or activity increases, that’s a pretty clear indication that the volcano is changing.</p><img src="https://counter.theconversation.com/content/195633/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Gabi Laske receives funding from the National Science Foundation. </span></em></p>A scientist who led one of the first projects to map the Hawaiian Islands’ deep volcanic plumbing explains what’s going on under the surface as Mauna Loa erupts.Gabi Laske, Professor of Geophysics, University of California, San DiegoLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1904312022-09-22T20:15:45Z2022-09-22T20:15:45ZCurious Kids: how is lava made?<figure><img src="https://images.theconversation.com/files/484971/original/file-20220915-40845-spyrev.jpg?ixlib=rb-1.1.0&rect=15%2C57%2C3469%2C2450&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">ImageBank4u/Shutterstock</span></span></figcaption></figure><blockquote>
<p>How is lava made? – Leon, age 7, Sydney, Australia </p>
</blockquote>
<p><a href="https://theconversation.com/au/topics/curious-kids-36782"><img src="https://images.theconversation.com/files/291898/original/file-20190911-190031-enlxbk.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=90&fit=crop&dpr=1" width="100%"></a></p>
<p>Thank you for a great question Leon! </p>
<p>Have you ever seen lava? What does it look like to you? Lava can be red, fiery and liquid or cool, dark and solid, like in the picture above. </p>
<p>In the picture you can see red hot lava, flowing over black solid rock where the lava has cooled. Lava is molten rock, melted because of very high temperatures, much, much hotter than you would see on the surface of the earth.</p>
<p>Can you imagine how hot it must be to melt rock? This gives a clue about how lava is made, somewhere with very high temperatures below Earth’s surface. </p>
<p>While underground, the liquid rock is called magma; it becomes lava when it flows onto the planet’s surface, usually through a volcano. When the lava cools – that’s the dark solid ground you see in the image – it is called “igneous” rock. This means “fire” in Latin (scientists use a lot of Latin words), so it is fire rock.</p>
<p>To understand how lava is made and where it comes from, we need to journey below Earth’s surface – which we can’t do, because it would be too dangerous. Imagine trying to travel somewhere hot enough to melt rock, what would that do to you?</p>
<p>Instead, we can look at the structure of Earth in the image below and imagine the journey.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/484976/original/file-20220915-46145-spyrev.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A chart showing Earth's crust, upper mantle, lower mantle, inner core like a dissected gumball" src="https://images.theconversation.com/files/484976/original/file-20220915-46145-spyrev.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/484976/original/file-20220915-46145-spyrev.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=600&fit=crop&dpr=1 600w, https://images.theconversation.com/files/484976/original/file-20220915-46145-spyrev.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=600&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/484976/original/file-20220915-46145-spyrev.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=600&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/484976/original/file-20220915-46145-spyrev.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=754&fit=crop&dpr=1 754w, https://images.theconversation.com/files/484976/original/file-20220915-46145-spyrev.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=754&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/484976/original/file-20220915-46145-spyrev.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=754&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Earth has several layers in its structure, from surface all the way to the solid core.</span>
<span class="attribution"><span class="source">Naeblys/Shutterstock</span></span>
</figcaption>
</figure>
<p>We would travel down through Earth’s crust, into the mantle and then into the core. Once there, we would discover that the crust and mantle are mostly solid rock. After the mantle we would notice the liquid outer core and then the solid metal inner core. </p>
<p>In Earth’s core the temperatures are very hot, <a href="https://www.nationalgeographic.com/science/article/earths-interior">usually between 5,000 and 7,000 degrees Celsius</a>. Think about this to compare: chocolate starts melting at around 80°C and tap water boils at 100°C. This very hot core acts like an oven for Earth, heating it from within.</p>
<p>Along the way we might find some magma in the mantle where it is made, in a space between the outer mantle and Earth’s crust. Magma is formed through heat and pressure – imagine squeezing a ball of plasticine as hard as you can: that is you putting pressure on the ball. While the mantle is not as hot as the liquid core, there is a lot more pressure. The pressure is caused by movement in the rocky mantle, pressing against the crust.</p>
<p>This pressure, and the temperatures from Earth’s “oven” at the core, cause rock to melt and magma is formed. The magma moves to Earth’s surface through openings – sometimes these openings are volcanoes – and forms new crust. </p>
<p>Often the new crust forms into islands, like many of the Pacific islands. This happens because liquid comes out through openings on the sea floor and cools, forming land.</p>
<p>You can watch this video for the story from Mother Earth herself. But be warned: never put rocks in a fire to try and melt them, some might explode! I’ll let you ask about that another time.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/SoJ8cRnbbps?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
</figure><img src="https://counter.theconversation.com/content/190431/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Janice Crerar does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>Earth has liquid rock inside. Here’s what happens to that rock to make lava happen.Janice Crerar, Lecturer in Education, Charles Darwin UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1895242022-09-22T19:51:23Z2022-09-22T19:51:23ZWe can use drones to get inside and learn more about active, gassy volcanoes<figure><img src="https://images.theconversation.com/files/485137/original/file-20220916-1799-a2tkgw.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C5208%2C3875&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">An overhead shot of a volcano crater in east Java, Indonesia.</span> <span class="attribution"><span class="source">(Shutterstock)</span></span></figcaption></figure><p>Volcanic eruptions cannot be predicted with 100 per cent certainty. However, details about an upcoming eruption can be estimated using the hot and smelly gases a volcano produces. </p>
<p>These gases provide clues about the timing, duration or severity of upcoming eruptions which can help local authorities decide if and when the surrounding communities need to be evacuated. </p>
<p>On average, there are <a href="https://volcano.si.edu/">up to 50 volcanoes</a> actively erupting on the planet at any given time. Many of these volcanoes are more likely to be spewing hot gases — like steam and carbon dioxide — than lava. Collecting these gases is key to understanding the mysterious ways of volcanoes, but it can be dangerous.</p>
<p>Now, <a href="https://doi.org/10.30909/vol.03.01.67114">drones are making it safer</a> and easier than ever before.</p>
<h2>Gassy volcanoes</h2>
<p>For the better part of the last decade, I have been visiting such gassy volcanoes regularly to catch them just before, during or after an eruption. </p>
<p>I have worked with other scientists and engineers to <a href="https://eos.org/science-updates/drones-swoop-in-to-measure-gas-belched-from-volcanoes">measure volcanic gases</a> with a variety of devices attached to drones. </p>
<p>Our latest research uses drones to <a href="https://doi.org/10.1016/j.jvolgeores.2022.107639">capture volcanic carbon dioxide at Poás volcano in Costa Rica</a>. We measured the isotopes of carbon in this carbon dioxide and discovered a pattern in the way these chemical fingerprints change during different stages of activity.</p>
<h2>Unique carbon makeup</h2>
<p>Carbon dioxide is everywhere: in the air we exhale, in vehicle exhaust — and dissolved in magma. At volcanoes, it escapes from magma to the surface through cracks and hydrothermal systems (like the geysers in Yellowstone National Park), by seeping through the soil or by puffing out in a plume of gas. </p>
<p>By obtaining a sample of this <a href="https://doi.org/10.2138/rmg.2013.75.11">volcanic carbon</a>, we can measure the stable carbon isotopic ratio, a unique chemical makeup which reflects the source and pathway the CO2 took to the surface. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/485139/original/file-20220916-8280-bzy2aj.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="a plume of smoke emerges from a hole in the ground" src="https://images.theconversation.com/files/485139/original/file-20220916-8280-bzy2aj.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/485139/original/file-20220916-8280-bzy2aj.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/485139/original/file-20220916-8280-bzy2aj.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/485139/original/file-20220916-8280-bzy2aj.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/485139/original/file-20220916-8280-bzy2aj.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/485139/original/file-20220916-8280-bzy2aj.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/485139/original/file-20220916-8280-bzy2aj.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Underground pressure forces gas and smoke out of the ground in the geysers in Yellowstone National Park.</span>
<span class="attribution"><span class="source">(Donna Elliot/Unsplash)</span></span>
</figcaption>
</figure>
<p>Each volcano around the world produces a unique range of these <a href="https://doi.org/10.1126/science.aan5049">carbon isotopes</a> which change when the volcanic system changes. </p>
<p>However, it took a long time to collect each sample when researchers needed to hike down into a crater, putting them at risk each second they remained in the danger zone. With the evolution of unoccupied aerial systems (UAS, also known as drones), researchers have started sending these machines into the danger areas.</p>
<h2>Employing drones</h2>
<p>To do this, we used switches and electronics parts to connect gas sensors to the onboard communications systems of the UAS. The volcanic CO2 would be sucked in through a series of tubing with the help of a pump and sensors that would send a signal back to the pilot when we entered the gas plume. With the flick of a switch on the remote control, the pilot could choose — from a safe distance — when and where to collect the gas sample. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/484123/original/file-20220912-1707-5fe5og.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C4898%2C3226&q=45&auto=format&w=1000&fit=clip"><img alt="A drone landed in front of smoke" src="https://images.theconversation.com/files/484123/original/file-20220912-1707-5fe5og.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C4898%2C3226&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/484123/original/file-20220912-1707-5fe5og.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/484123/original/file-20220912-1707-5fe5og.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/484123/original/file-20220912-1707-5fe5og.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/484123/original/file-20220912-1707-5fe5og.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/484123/original/file-20220912-1707-5fe5og.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/484123/original/file-20220912-1707-5fe5og.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">A drone equipped to sample volcanic gas captures carbon dioxide.</span>
<span class="attribution"><span class="source">(Fiona D'Arcy)</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>We arrived in Costa Rica in April 2019 with our shiny new drone set-up, which we launched at the rim of Poás volcano and which crashed almost immediately. Thankfully, our team whipped up a quick solution for our second drone — a pump and switch hanging from the drone in a laundry bag. It worked flawlessly.</p>
<p>To avoid further losses, we got up close to the crater and flew our assembly directly above it. Later that day, we looked at the stable isotopes of carbon in our drone samples and in the samples we took from the ground. After we accounted for the mixing with the regular air in the drone samples, the two results were strikingly similar. Our drone assembly worked!</p>
<h2>A pattern emerges</h2>
<p>When we started compiling our data with all the carbon isotopes measured at Poás volcano in the past, we noticed a trend in how the balance of isotopes shifted when the volcano was behaving differently. </p>
<p>During eruptive phases, when Poás was making wet explosions releasing extra hot, sulfur-rich gas, the isotopes of carbon slipped down to lighter values. Meanwhile, during quieter phases <a href="https://doi.org/10.1016/j.jvolgeores.2021.107297">when the volcano was sealed</a>, the isotopic balance rose to heavier values. </p>
<p>With this new insight, we could look back even further and stitch together our data with <a href="https://doi.org/10.1007/978-3-319-02156-0_10">isotope data from older activity</a>. We saw that this pattern was repeating itself, with the carbon isotopes alternating between heavy an light values over the last 20 years of activity at Poás. There were relatively heavy values when the volcano was sealed and there were relatively light values when the volcano was open. </p>
<p>We now have a blueprint of what warning signals to look for in future isotopes of carbon sampled at this volcano when it’s gearing up to erupt.</p>
<p><div data-react-class="Tweet" data-react-props="{"tweetId":"1298020478691549190"}"></div></p>
<h2>Future research</h2>
<p>Thanks to drones, we captured the first CO2 from Poás volcano since 2014. Volcanic gases sampled before our work were all taken by hand by brave volcano scientists climbing down into the crater of Poás. These expeditions were few and far between. </p>
<p>We hope that with the onset of gas-capturing drones, carbon dioxide at volcanoes <a href="https://doi.org/10.1126/sciadv.abb9103">can start to be sampled more frequently</a>. This will fill the gaps in the timeline and help us understand and forecast eruptions.</p><img src="https://counter.theconversation.com/content/189524/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Fiona D'Arcy receives funding from the Vanier Canada Graduate Scholarships (Vanier CGS). </span></em></p>Drones can be used to collect gas samples from active volcanoes, where it is too dangerous for researchers. This data can be then used to predict the frequency and severity of eruptions.Fiona D'Arcy, PhD candidate in Earth Sciences, McGill UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1881582022-08-24T03:19:00Z2022-08-24T03:19:00ZScientists have traced Earth’s path through the galaxy via tiny crystals found in the crust<figure><img src="https://images.theconversation.com/files/479303/original/file-20220816-24-ywqf10.jpg?ixlib=rb-1.1.0&rect=1274%2C67%2C4513%2C2491&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">Triff/Shutterstock</span></span></figcaption></figure><p>“To see a world in a grain of sand”, the opening sentence of the poem by <a href="https://www.poetryfoundation.org/poems/43650/auguries-of-innocence">William Blake</a>, is an oft-used phrase that also captures some of what geologists do.</p>
<p>We observe the composition of mineral grains, smaller than the width of a human hair. Then, we extrapolate the chemical processes they suggest to ponder <a href="https://eos.org/science-updates/earths-continents-share-an-ancient-crustal-ancestor">the construction of our planet</a> itself.</p>
<p>Now, we’ve taken that minute attention to new heights, connecting tiny grains to Earth’s place in the galactic environment.</p>
<h2>Looking out to the universe</h2>
<p>At an even larger scale, astrophysicists seek to understand the universe and our place in it. They use laws of physics to develop models that describe the orbits of astronomical objects.</p>
<p>Although we may think of the planet’s surface as something shaped by processes entirely within Earth itself, our planet has undoubtedly felt the effects of its cosmic environment. This includes <a href="https://www.nature.com/scitable/knowledge/library/milankovitch-cycles-paleoclimatic-change-and-hominin-evolution-68244581/">periodic changes in Earth’s orbit</a>, variations in the Sun’s output, gamma ray bursts, and of course meteorite impacts.</p>
<p>Just looking at the Moon and its pockmarked surface should remind us of that, given Earth is more than 80 times more massive than its grey satellite. In fact, recent work has pointed to the importance of meteorite impacts in the <a href="https://www.nature.com/articles/s41586-022-04956-y">production of continental crust on Earth</a>, helping to form buoyant “seeds” that floated on the outermost layer of our planet in its youth.</p>
<p>We and our international team of colleagues have now identified a rhythm in the production of this early continental crust, and the tempo points to a truly grand driving mechanism. This work has just been published <a href="https://doi.org/10.1130/G50513.1">in the journal Geology</a>.</p>
<figure class="align-center ">
<img alt="A swirling spiral of blue and white glowing stars on a dark background" src="https://images.theconversation.com/files/477930/original/file-20220806-35739-ito9l9.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/477930/original/file-20220806-35739-ito9l9.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=648&fit=crop&dpr=1 600w, https://images.theconversation.com/files/477930/original/file-20220806-35739-ito9l9.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=648&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/477930/original/file-20220806-35739-ito9l9.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=648&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/477930/original/file-20220806-35739-ito9l9.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=814&fit=crop&dpr=1 754w, https://images.theconversation.com/files/477930/original/file-20220806-35739-ito9l9.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=814&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/477930/original/file-20220806-35739-ito9l9.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=814&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Residing inside the Milky Way galaxy makes it impossible to picture, but our galaxy is thought to be similar to other barred spiral galaxies, like NGC 4394.</span>
<span class="attribution"><span class="source">ESA/Hubble & NASA</span></span>
</figcaption>
</figure>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/what-created-the-continents-new-evidence-points-to-giant-asteroids-185606">What created the continents? New evidence points to giant asteroids</a>
</strong>
</em>
</p>
<hr>
<h2>The rhythm of crust production on Earth</h2>
<p>Many rocks on Earth form from molten or semi-molten magma. This magma is derived either directly from the mantle – the predominantly solid but slowly flowing layer below the planet’s crust – or from recooking even older bits of pre-existing crust. As liquid magma cools, it eventually freezes into solid rock.</p>
<p>Through this cooling process of magma crystallisation, mineral grains grow and can trap elements such as uranium that decay over time and produce a sort of stopwatch, <a href="https://www.gsoc.org/news/2020/12/07/zircon">recording their age</a>. Not only that, but crystals can also trap <a href="https://www.nature.com/articles/srep38503">other elements</a> that track the composition of their parental magma, like how a surname might track a person’s family.</p>
<p>With these two pieces of information – age and composition – we can then reconstruct a timeline of crust production. Then, we can decode its main frequencies, using the mathematical wizardry of the <a href="https://betterexplained.com/articles/an-interactive-guide-to-the-fourier-transform/">Fourier transform</a>. This tool basically decodes the frequency of events, much like unscrambling ingredients that have gone into the blender for a cake.</p>
<p>Our results from this approach suggest an approximate 200-million-year rhythm to crust production on the early Earth.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/ancient-earth-had-a-thick-toxic-atmosphere-like-venus-until-it-cooled-off-and-became-liveable-150934">Ancient Earth had a thick, toxic atmosphere like Venus – until it cooled off and became liveable</a>
</strong>
</em>
</p>
<hr>
<h2>Our place in the cosmos</h2>
<p>But there is another process with a similar rhythm. Our Solar System and the four spiral arms of the Milky Way are both spinning around the supermassive black hole at the galaxy’s centre, yet they are moving at different speeds.</p>
<p>The spiral arms orbit at 210 kilometres per second, while the Sun is speeding along at 240km per second, meaning our Solar System is surfing into and out of the galaxy’s arms. You can think of the spiral arms as dense regions that slow the passage of stars much like a traffic jam, which only clears further down the road (or through the arm).</p>
<figure class="align-center ">
<img alt="Geological events on the orbit of the solar system in the Milky Way galaxy" src="https://images.theconversation.com/files/477931/original/file-20220806-35905-yvr1i6.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/477931/original/file-20220806-35905-yvr1i6.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/477931/original/file-20220806-35905-yvr1i6.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/477931/original/file-20220806-35905-yvr1i6.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/477931/original/file-20220806-35905-yvr1i6.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=502&fit=crop&dpr=1 754w, https://images.theconversation.com/files/477931/original/file-20220806-35905-yvr1i6.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=502&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/477931/original/file-20220806-35905-yvr1i6.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=502&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Geological events, including major crust formation events highlighted on the transit of the Solar System through the galactic spiral arms.</span>
<span class="attribution"><span class="source">NASA/JPL-Caltech/ESO/R. Hurt (background image)</span></span>
</figcaption>
</figure>
<p>This model results in approximately 200 million years between each entry our Solar System makes into a spiral arm of the galaxy.</p>
<p>So, there seems to be a possible connection between the timing of crust production on Earth and the length of time it takes to orbit the galactic spiral arms – but why?</p>
<h2>Strikes from the cloud</h2>
<p>In the distant reaches of our Solar System, a cloud of icy rocky debris named the <a href="https://solarsystem.nasa.gov/solar-system/oort-cloud/overview%5D">Oort cloud</a> is thought to orbit our Sun.</p>
<p>As the Solar System periodically moves into a spiral arm, interaction between it and the Oort cloud is proposed to dislodge material from the cloud, sending it closer to the inner Solar System. Some of this material may even strike Earth.</p>
<figure class="align-center ">
<img alt="A glowing image of a spiral galaxy with blue arms and pale golden centre" src="https://images.theconversation.com/files/479311/original/file-20220816-26-hmqoph.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/479311/original/file-20220816-26-hmqoph.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/479311/original/file-20220816-26-hmqoph.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/479311/original/file-20220816-26-hmqoph.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/479311/original/file-20220816-26-hmqoph.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/479311/original/file-20220816-26-hmqoph.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/479311/original/file-20220816-26-hmqoph.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Milky Way’s structure and Solar System’s orbit through it may be important in controlling the frequency of some large impacts on Earth, which in turn may have seeded crust production on the early Earth.</span>
<span class="attribution"><span class="source">jivacore/Shutterstock</span></span>
</figcaption>
</figure>
<p>Earth experiences relatively frequent impacts from the rocky bodies of the asteroid belt, which on average arrive at speeds of 15km per second. But comets ejected from the Oort cloud arrive much faster, on average 52km per second.</p>
<p>We argue it is these periodic high-energy impacts that are tracked by the record of crust production preserved in <a href="https://knowablemagazine.org/article/physical-world/2021/keeping-time-zircons">tiny mineral grains</a>. Comet impacts excavate huge volumes of Earth’s surface, leading to decompression melting of the mantle, not too dissimilar from popping a cork on a bottle of fizz.</p>
<p>This molten rock, enriched in light elements such as silicon, aluminium, sodium and potassium, effectively floats on the denser mantle. While there are many other ways to <a href="https://theconversation.com/just-add-mantle-water-new-research-cracks-the-mystery-of-how-the-first-continents-formed-156845">generate continental crust</a>, it’s likely that <a href="https://www.nature.com/articles/s41467-019-08467-9">impacting</a> on our early planet formed buoyant seeds of crust. Magma produced from later geological processes would adhere to those early seeds.</p>
<h2>Harbingers of doom, or gardeners for terrestrial life?</h2>
<p>Continental crust is vital in most of Earth’s natural cycles – it interacts with water and oxygen, forming new weathered products, hosting most metals and biological carbon.</p>
<p>Large meteorite impacts are cataclysmic events that <a href="https://theconversation.com/more-bad-news-for-dinosaurs-chicxulub-meteorite-impact-triggered-global-volcanic-eruptions-on-the-ocean-floor-91053">can obliterate life</a>. Yet, impacts may very well have been key to the development of the continental crust we live on.</p>
<p>With the recent passage of <a href="https://theconversation.com/mysterious-alien-cigar-asteroid-is-actually-an-interstellar-lump-of-ice-not-a-space-ship-89322">interstellar asteroids</a> through the Solar System, some have even gone so far as to suggest they <a href="https://www.daviddarling.info/encyclopedia/P/panspermia.html">ferried life across the cosmos</a>.</p>
<p>However we came to be here, it is awe-inspiring on a clear night to look up at the sky and see the stars and the structure they trace, and then look down at your feet and feel the mineral grains, rock and continental crust below – all linked through a very grand rhythm indeed.</p><img src="https://counter.theconversation.com/content/188158/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Chris Kirkland receives funding from the Australian Research Council.</span></em></p><p class="fine-print"><em><span>Phil Sutton does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>There’s a curious 200-million-year rhythm to Earth’s crust production. Now, it seems like our very place in the galaxy is tied to it.Chris Kirkland, Professor of Geology, Curtin UniversityPhil Sutton, Senior Lecturer in Astrophysics, University of LincolnLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1750352022-01-15T20:04:22Z2022-01-15T20:04:22ZWhy the volcanic eruption in Tonga was so violent, and what to expect next<p>The Kingdom of Tonga doesn’t often attract global attention, but a <a href="https://www.rnz.co.nz/international/pacific-news/459572/underwater-volcano-hunga-tonga-hunga-ha-apai-erupts-again">violent eruption of an underwater volcano</a> on January 15 has spread shock waves, quite literally, around half the world. </p>
<p><div data-react-class="Tweet" data-react-props="{"tweetId":"1482259999724535809"}"></div></p>
<p>The volcano is usually not much to look at. It consists of two small uninhabited islands, Hunga-Ha’apai and Hunga-Tonga, poking about 100m above sea level 65km north of Tonga’s capital Nuku‘alofa. But hiding below the waves is a massive volcano, around 1800m high and 20km wide.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/440948/original/file-20220115-27-82tzyq.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A map of the massive underwater volcano next to the Hunga-Ha’apai and Hunga-Tonga islands." src="https://images.theconversation.com/files/440948/original/file-20220115-27-82tzyq.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/440948/original/file-20220115-27-82tzyq.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=658&fit=crop&dpr=1 600w, https://images.theconversation.com/files/440948/original/file-20220115-27-82tzyq.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=658&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/440948/original/file-20220115-27-82tzyq.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=658&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/440948/original/file-20220115-27-82tzyq.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=827&fit=crop&dpr=1 754w, https://images.theconversation.com/files/440948/original/file-20220115-27-82tzyq.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=827&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/440948/original/file-20220115-27-82tzyq.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=827&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">A massive underwater volcano lies next to the Hunga-Ha’apai and Hunga-Tonga islands.</span>
<span class="attribution"><span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>The Hunga-Tonga-Hunga-Ha'apai volcano has erupted regularly over the past few decades. During events in 2009 and 2014/15 hot jets of magma and steam exploded through the waves. But these eruptions were small, dwarfed in scale by the January 2022 events.</p>
<p>Our <a href="https://eos.org/science-updates/new-volcanic-island-unveils-explosive-past">research</a> into these earlier eruptions suggests this is one of the massive explosions the volcano is capable of producing roughly every thousand years. </p>
<p>Why are the volcano’s eruptions so highly explosive, given that sea water should cool the magma down?</p>
<p>If magma rises into sea water slowly, even at temperatures of about 1200°C, a thin film of steam forms between the magma and water. This provides a layer of insulation to allow the outer surface of the magma to cool. </p>
<p>But this process doesn’t work when magma is blasted out of the ground full of volcanic gas. When magma enters the water rapidly, any steam layers are quickly disrupted, bringing hot magma in direct contact with cold water. </p>
<p>Volcano researchers call this “fuel-coolant interaction” and it is akin to weapons-grade chemical explosions. Extremely violent blasts tear the magma apart. A chain reaction begins, with new magma fragments exposing fresh hot interior surfaces to water, and the explosions repeat, ultimately jetting out volcanic particles and causing blasts with supersonic speeds. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/the-pulse-of-a-volcano-can-be-used-to-help-predict-its-next-eruption-117005">The 'pulse' of a volcano can be used to help predict its next eruption</a>
</strong>
</em>
</p>
<hr>
<h2>Two scales of Hunga eruptions</h2>
<p>The 2014/15 eruption created a volcanic cone, joining the two old Hunga islands to create a combined island about 5km long. We visited in 2016, and discovered these historical eruptions were merely <a href="https://eos.org/science-updates/new-volcanic-island-unveils-explosive-past">curtain raisers to the main event</a>. </p>
<p>Mapping the sea floor, we discovered a hidden “caldera” 150m below the waves. </p>
<figure class="align-center ">
<img alt="A map of the seafloor shows the volcanic cones and caldera." src="https://images.theconversation.com/files/440944/original/file-20220115-19-nplel8.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/440944/original/file-20220115-19-nplel8.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=660&fit=crop&dpr=1 600w, https://images.theconversation.com/files/440944/original/file-20220115-19-nplel8.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=660&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/440944/original/file-20220115-19-nplel8.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=660&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/440944/original/file-20220115-19-nplel8.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=829&fit=crop&dpr=1 754w, https://images.theconversation.com/files/440944/original/file-20220115-19-nplel8.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=829&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/440944/original/file-20220115-19-nplel8.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=829&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">A map of the seafloor shows the volcanic cones and massive caldera.</span>
<span class="attribution"><span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>The caldera is a crater-like depression around 5km across. Small eruptions (such as in 2009 and 2014/15) occur mainly at the edge of the caldera, but very big ones come from the caldera itself. These big eruptions are so large the top of the erupting magma collapses inward, deepening the caldera. </p>
<p>Looking at the chemistry of past eruptions, we now think the small eruptions represent the magma system slowly recharging itself to prepare for a big event.</p>
<p>We found evidence of two huge past eruptions from the Hunga caldera in deposits on the old islands. We matched these chemically to volcanic ash deposits on the largest inhabited island of Tongatapu, 65km away, and then used radiocarbon dates to show that big caldera eruptions occur about ever 1000 years, with the last one at AD1100. </p>
<p>With this knowledge, the eruption on January 15 seems to be right on schedule for a “big one”. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/why-white-island-erupted-and-why-there-was-no-warning-128550">Why White Island erupted and why there was no warning</a>
</strong>
</em>
</p>
<hr>
<h2>What we can expect to happen now</h2>
<p>We’re still in the middle of this major eruptive sequence and many aspects remain unclear, partly because the island is currently obscured by ash clouds. </p>
<p>The two earlier eruptions on December 20 2021 and January 13 2022 were of moderate size. They produced clouds of up to 17km elevation and added new land to the 2014/15 combined island.</p>
<p>The latest eruption has stepped up the scale in terms of violence. The ash plume is already about 20km high. Most remarkably, it spread out almost concentrically over a distance of about 130km from the volcano, creating a plume with a 260km diameter, before it was distorted by the wind. </p>
<p><img src="https://cdn.theconversation.com/static_files/files/1920/2022-01_volcano_jan_13_ash%281%29.gif?1642274062" width="100%"></p>
<p>This demonstrates a huge explosive power – one that cannot be explained by magma-water interaction alone. It shows instead that large amounts of fresh, gas-charged magma have erupted from the caldera.</p>
<p>The eruption also produced a <a href="https://www.theguardian.com/world/2022/jan/15/tonga-tsunami-warning-as-volcano-erupts-at-sea">tsunami throughout Tonga</a> and neighbouring Fiji and Samoa. Shock waves traversed many thousands of kilometres, were seen from space, and recorded in New Zealand some 2000km away. Soon after the eruption started, the sky was blocked out on Tongatapu, with ash beginning to fall.</p>
<p>All these signs suggest the large Hunga caldera has awoken. Tsunami are generated by coupled atmospheric and ocean shock waves during an explosion, but they are also readily caused by submarine landslides and caldera collapses.</p>
<p><div data-react-class="Tweet" data-react-props="{"tweetId":"1473857092364771336"}"></div></p>
<p>It remains unclear if this is the climax of the eruption. It represents a major magma pressure release, which may settle the system. </p>
<p>A warning, however, lies in geological deposits from the volcano’s previous eruptions. These complex sequences show each of the 1000-year major caldera eruption episodes involved many separate explosion events. </p>
<p>Hence we could be in for several weeks or even years of major volcanic unrest from the Hunga-Tonga-Hunga-Ha'apai volcano. For the sake of the people of Tonga I hope not.</p><img src="https://counter.theconversation.com/content/175035/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Shane Cronin receives funding from The University of Auckland Faculty of Science to study the 2014-2015 Hunga eruption.</span></em></p>The eruption is akin to a weapons-grade chemical explosion, and there could be several weeks or even years of major volcanic unrest to follow.Shane Cronin, Professor of Earth Sciences, University of Auckland, Waipapa Taumata RauLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1673582021-09-15T20:03:58Z2021-09-15T20:03:58ZThere she blows: the internal ‘magma filter’ that prompts ocean island volcanoes to erupt<figure><img src="https://images.theconversation.com/files/421297/original/file-20210915-26-ilinv0.JPG?ixlib=rb-1.1.0&rect=6%2C172%2C4594%2C2890&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">Laura Becerril</span>, <span class="license">Author provided</span></span></figcaption></figure><p>The volcanoes we see on Earth’s surface are just the tip of the iceberg. Beneath the surface, they are fed by a complex network of conduits and reservoirs that bring molten rock, called magma, to the surface.</p>
<p>When the magma erupts, it can generate lava flows that cool down to become volcanic rocks. These rocks hold key clues about volcanoes’ inner workings, and what triggered them to erupt in the past. But decoding these clues is a puzzling task.</p>
<p>Our new research, <a href="https://doi.org/10.1130/G49224.1">published in the journal Geology</a>, reveals previously hidden information in the chemistry of erupted lavas. Intriguingly, we discovered that many volcanoes have an internal “filter” that prompts them to erupt.</p>
<p>If we can detect magma at this crucial tipping point inside the volcano, it might even help us detect when an eruption is imminent.</p>
<h2>Hotspot volcanoes</h2>
<p>Most volcanoes, such as those in the Pacific Ring of Fire and the mid-Atlantic, are at the boundaries between <a href="https://www.nationalgeographic.org/media/plate-tectonics/">tectonic plates</a>. But some volcanoes, including the ones that created the Hawaiian islands, occur where hot plumes from deep inside Earth reach the surface. These are known as “hotspot” volcanoes.</p>
<p>Australia hosts the <a href="https://www.nature.com/articles/nature14903">longest track</a> of hotspot volcanoes in a continental setting. Over tens of millions of years, volcanoes such as The Glass House Mountains in Queensland, or Wollumbin (Mount Warning) in New South Wales, tracked the movement of the Australian continent over a stationary hotspot.</p>
<p>In the oceans, hotspots build chains of paradise islands such as Hawaii, the Galapagos or the Canary Islands. These ocean island volcanoes were previously thought to have been made of magma that welled up from tens of kilometres beneath the surface, deep in Earth’s mantle.</p>
<p>But our new research suggests ocean island volcanoes may erupt magma that has been filtered and modified at shallower depth.</p>
<h2>Crystal-rich, not crystal clear</h2>
<p>Volcanic lavas often contain crystals from inside the volcano, that were mixed in with the erupting magma. The crystals tell us a lot about the volcano’s insides, but they can also <a href="https://www.sciencedirect.com/science/article/pii/S0012821X21001631">disguise the chemistry of the lava itself</a>.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/volcano-crystals-could-make-it-easier-to-predict-eruptions-90558">Volcano crystals could make it easier to predict eruptions</a>
</strong>
</em>
</p>
<hr>
<p>Think of it like rocky road chocolate. If we want to analyse the ingredients of the chocolate itself, we first need to disregard the marshmallows and nuts.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/421282/original/file-20210915-14-1rjsbsw.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Microscopic image of crystals in magma." src="https://images.theconversation.com/files/421282/original/file-20210915-14-1rjsbsw.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/421282/original/file-20210915-14-1rjsbsw.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=449&fit=crop&dpr=1 600w, https://images.theconversation.com/files/421282/original/file-20210915-14-1rjsbsw.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=449&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/421282/original/file-20210915-14-1rjsbsw.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=449&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/421282/original/file-20210915-14-1rjsbsw.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=564&fit=crop&dpr=1 754w, https://images.theconversation.com/files/421282/original/file-20210915-14-1rjsbsw.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=564&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/421282/original/file-20210915-14-1rjsbsw.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=564&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Microscopic image of crystals in magma.</span>
<span class="attribution"><span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>We can do this by analysing rocks made from crystal-free lavas. In our study, we compared crystal-free and crystal-rich magmas from El Hierro volcano in the Canary Islands, which last erupted in 2011.</p>
<p>It turns out that the crystal-free magma from these volcanoes is very similar across millions of years of volcanic activity, and across many ocean island volcanoes around the world, including the Canary Islands and Hawaii. This is how we realised the magma was not pristine and coming directly from great depth, but rather filtered at shallower depths.</p>
<p>And if the magma from hotspot island volcanoes is so similar, the chances are their eruptions are triggered by common mechanisms too.</p>
<h2>The ‘secret volcano filter’</h2>
<p>When crystals form inside the volcano, this “steals” chemical elements from the magma. In turn, this alters the composition of the leftover magma, almost as if it had been passed through a sieve. </p>
<p>This filtering process makes the magma less dense, and increases its gas content. This gas can then bubble up and propel the magma to the surface, just like the cork popping from a bottle of champagne.</p>
<p>In ocean island volcanoes, the magma can reach this “tipping point” at the base of the Earth’s crust, just a few kilometres beneath the surface, rather than at depth.
This means that if we detect magma at this depth with the help of earthquake monitoring equipment, an eruption might follow. This is exactly what happened when <a href="https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2012GL051846">El Hierro erupted in 2011</a>.</p>
<h2>Does this make it easier to forecast eruptions?</h2>
<p>If we could open a volcano like a doll’s house, we would be able to track the movement of magma towards the surface. It’s a pity we can’t, although we can try to “see” this journey indirectly, by <a href="https://www.usgs.gov/natural-hazards/volcano-hazards/monitoring">monitoring</a> earthquakes, deformation and gas emissions, all of which can indicate magma rising inside a volcano.</p>
<p>But to assess whether a volcano is likely to erupt, or whether a dormant volcano is reawakening, we also need to compare current observations with information about what triggered eruptions in the <a href="https://www.sciencedirect.com/science/article/pii/S0377027321001943">past</a>.</p>
<p>This is where our new discovery could prove especially useful. If the eruption triggers happen at similar depths in ocean island volcanoes globally, warning signs from such depths may be particularly important to monitor and consider as the precursory signs of eruption.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/australias-volcanic-history-is-a-lot-more-recent-than-you-think-58766">Australia's volcanic history is a lot more recent than you think</a>
</strong>
</em>
</p>
<hr>
<img src="https://counter.theconversation.com/content/167358/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Teresa Ubide receives funding from The University of Queensland, the Queensland Government and the Australian Research Council.</span></em></p>A previously unknown filtering process inside some volcanoes can cause magma to shoot out like champagne from a bottle - and perhaps even make it easier to forecast when a volcano is about to erupt.Teresa Ubide, Senior Lecturer in Igneous Petrology/Volcanology, The University of QueenslandLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1611762021-06-02T20:06:32Z2021-06-02T20:06:32ZPhotos from the field: the stunning crystals revealing deep secrets about Australian volcanoes<figure><img src="https://images.theconversation.com/files/403875/original/file-20210601-13-1kcoq9j.jpg?ixlib=rb-1.1.0&rect=36%2C84%2C3989%2C3024&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">This isn't a painting or a stained-glass window — it's a microscope image of light shining through the Earth's mantle. </span> <span class="attribution"><span class="source">Heather Handley</span>, <span class="license">Author provided</span></span></figcaption></figure><p><em>Environmental scientists see flora, fauna and phenomena the rest of us rarely do. In this series, we’ve invited them to share their unique <a href="https://theconversation.com/au/topics/photos-from-the-field-92499">photos from the field</a>.</em></p>
<hr>
<p>Volcanic activity is a constant global threat. It’s estimated over <a href="https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=&cad=rja&uact=8&ved=2ahUKEwiIqcmkyfLwAhWK4zgGHWPiDGkQFjADegQIBhAD&url=https%3A%2F%2Fwww.mdpi.com%2F2220-9964%2F8%2F8%2F341%2Fpdf&usg=AOvVaw2smkdZhL8rlzzyfjwu8sgV">1 billion people</a> live within the potential, direct impact range of volcanic eruptions. </p>
<p>Just recently, lava flows from the eruption of <a href="https://theconversation.com/mount-nyiragongos-volcano-why-its-unique-and-treacherous-161847">Mount Nyiragongo</a>, a volcano in the Democratic Republic of Congo, killed <a href="https://www.unicef.org/press-releases/280000-children-face-displacement-because-drc-volcano-threat">32 people</a>, with many more missing. Tens of thousands of people have been forced to flee the city of Goma.</p>
<p>This shows why understanding more about the inner workings of volcanoes is critical to improve the safety of those living in their shadows. </p>
<p>As a volcano scientist, my research takes me across Australia and all over the world. But sometimes, the most stunning revelations actually occur in the lab.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/403883/original/file-20210602-21-kqs7gu.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Heather Handley wearing a gas mask" src="https://images.theconversation.com/files/403883/original/file-20210602-21-kqs7gu.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/403883/original/file-20210602-21-kqs7gu.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/403883/original/file-20210602-21-kqs7gu.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/403883/original/file-20210602-21-kqs7gu.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/403883/original/file-20210602-21-kqs7gu.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/403883/original/file-20210602-21-kqs7gu.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/403883/original/file-20210602-21-kqs7gu.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Heather Handley at Ambrym volcano in Vanuatu, wearing a mask due the hazardous volcanic gases present.</span>
<span class="attribution"><span class="source">Heather Handley</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>I take a microscopic look at volcanic rocks and fragments of the Earth’s mantle to estimate just how fast molten rock (magma) moves from deep in the Earth to the surface. This can help us prepare for future eruptions. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/403880/original/file-20210602-25-8j69md.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/403880/original/file-20210602-25-8j69md.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/403880/original/file-20210602-25-8j69md.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/403880/original/file-20210602-25-8j69md.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/403880/original/file-20210602-25-8j69md.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/403880/original/file-20210602-25-8j69md.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/403880/original/file-20210602-25-8j69md.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/403880/original/file-20210602-25-8j69md.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">A slice of the Earth’s mantle under a microscope, and the colourful crystals it reveals. Different types of crystals (minerals) and different orientations of the same minerals produce the range in colours seen when cross-polarised light passes through them.</span>
<span class="attribution"><span class="source">Heather Handley</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<h2>Australia’s fiery past — and future</h2>
<p>Since the demise of the dinosaurs to recent human settlement, magmatic activity has left behind a trail of volcanoes stretching over 4,000 kilometres down Australia’s eastern margin, forming one of the world’s most extensive volcanic belts. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/australias-volcanic-history-is-a-lot-more-recent-than-you-think-58766">Australia's volcanic history is a lot more recent than you think</a>
</strong>
</em>
</p>
<hr>
<p>The last mainland eruptions took place at Mount Gambier and Mount Schank in South Australia around 5,000 years ago, a mere blink of a geological eye. </p>
<p>These eruptions were witnessed by local Aboriginal people and incorporated into oral traditions that have been passed down for hundreds of <a href="https://www.sciencedirect.com/science/article/abs/pii/S1871101416300826">generations</a>.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/NjkBETUXGWo?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">View from the crater of Mount Schank volcano, one of the youngest volcanoes in Australia. Credit Heather Handley.</span></figcaption>
</figure>
<p>Based on the time since the last eruption, there are potentially two active volcanic regions in mainland Australia: in the northeast (southwest of Cairns) and southeast (from Melbourne across into South Australia).</p>
<p>The Mount Gambier and Mount Schank volcanoes are two of more than 400 volcanoes in the <a href="https://volcano.oregonstate.edu/faq/how-volcano-defined-being-active-dormant-or-extinct">active</a> southeast region called the Newer Volcanics Province, which has been active for at least the last 4.5 million years. </p>
<p>It’s considered likely there’ll be a future eruption in this province, but it’s not known when or where exactly the eruption will be.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/403882/original/file-20210602-25-1cwzwps.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Volcanic eruption" src="https://images.theconversation.com/files/403882/original/file-20210602-25-1cwzwps.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/403882/original/file-20210602-25-1cwzwps.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/403882/original/file-20210602-25-1cwzwps.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/403882/original/file-20210602-25-1cwzwps.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/403882/original/file-20210602-25-1cwzwps.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/403882/original/file-20210602-25-1cwzwps.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/403882/original/file-20210602-25-1cwzwps.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Yasur volcano in Vanuatu, one of the most active volcanoes on the planet.</span>
<span class="attribution"><span class="source">Heather Handley</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/403884/original/file-20210602-25-xk8lg.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/403884/original/file-20210602-25-xk8lg.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/403884/original/file-20210602-25-xk8lg.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/403884/original/file-20210602-25-xk8lg.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/403884/original/file-20210602-25-xk8lg.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/403884/original/file-20210602-25-xk8lg.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/403884/original/file-20210602-25-xk8lg.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/403884/original/file-20210602-25-xk8lg.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The volcanic deposits of Ohakune volcano in New Zealand. The different coloured layers represent variations in eruption style and explosive power.</span>
<span class="attribution"><span class="source">Heather Handley</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<h2>So how much warning time might we have?</h2>
<p>To answer this question, we have to unravel the secrets held by past eruptions, now locked away in the erupted rocks and the crystals within them.</p>
<p>Our first clue is that many of the dark black volcanic rocks that erupted in the Newer Volcanics Province (and others) contain chunks of green rock, called peridotite. </p>
<p>These dense green rock fragments are, in fact, pieces of the Earth’s upper mantle that were plucked out by the rising magma and carried all the way to the surface from depths of greater than 30 or 40 kilometres below our feet. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/403527/original/file-20210531-21-1j4tpr0.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/403527/original/file-20210531-21-1j4tpr0.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=502&fit=crop&dpr=1 600w, https://images.theconversation.com/files/403527/original/file-20210531-21-1j4tpr0.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=502&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/403527/original/file-20210531-21-1j4tpr0.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=502&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/403527/original/file-20210531-21-1j4tpr0.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=630&fit=crop&dpr=1 754w, https://images.theconversation.com/files/403527/original/file-20210531-21-1j4tpr0.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=630&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/403527/original/file-20210531-21-1j4tpr0.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=630&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">A black volcanic bomb from Mount Noorat volcano in the Newer Volcanics Province containing peridotite xenoliths — green fragments of the Earth’s upper mantle.</span>
<span class="attribution"><span class="source">Heather Handley</span></span>
</figcaption>
</figure>
<p>These fragments can sink back down through the liquid rock during its ascent, like a pebble dropped into a cylinder of honey. So in order to reach the surface, the rising magma had to move fast — likely taking just a few days from the source.</p>
<h2>Volcanic crystal balls</h2>
<p>In the same way <a href="https://theconversation.com/we-found-a-secret-history-of-megadroughts-written-in-tree-rings-the-wheatbelts-future-may-be-drier-than-we-thought-160526">tree rings</a> can tell you about what the climate was like when the tree grew, the crystals within volcanic rocks and the mantle fragments they carry preserve memories of the environment on their upward journey through the Earth.</p>
<p>In the photo below, you can see how cross-polarised light passing through the mantle rock reveals a mosaic of colourful crystals. The darker part is the enclosing volcanic rock. </p>
<p>This thin slice of rock is just 30 microns in thickness, about half the thickness of a typical human hair.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/403535/original/file-20210531-21-m4nyfz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/403535/original/file-20210531-21-m4nyfz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=365&fit=crop&dpr=1 600w, https://images.theconversation.com/files/403535/original/file-20210531-21-m4nyfz.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=365&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/403535/original/file-20210531-21-m4nyfz.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=365&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/403535/original/file-20210531-21-m4nyfz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=459&fit=crop&dpr=1 754w, https://images.theconversation.com/files/403535/original/file-20210531-21-m4nyfz.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=459&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/403535/original/file-20210531-21-m4nyfz.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=459&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Microscope image of a rock from Mount Quincan volcano in the Atherton Volcanic Province, Queensland.</span>
<span class="attribution"><span class="source">Heather Handley</span></span>
</figcaption>
</figure>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/403886/original/file-20210602-15-14p85v5.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/403886/original/file-20210602-15-14p85v5.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/403886/original/file-20210602-15-14p85v5.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/403886/original/file-20210602-15-14p85v5.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/403886/original/file-20210602-15-14p85v5.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/403886/original/file-20210602-15-14p85v5.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/403886/original/file-20210602-15-14p85v5.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/403886/original/file-20210602-15-14p85v5.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">A section of lava from Mount Gambier, the youngest volcano in Australia. The larger crystals grew before the smaller crystals, which formed near or at the surface.</span>
<span class="attribution"><span class="source">Heather Handley</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/403896/original/file-20210602-17-147g5xw.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/403896/original/file-20210602-17-147g5xw.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/403896/original/file-20210602-17-147g5xw.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/403896/original/file-20210602-17-147g5xw.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/403896/original/file-20210602-17-147g5xw.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/403896/original/file-20210602-17-147g5xw.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/403896/original/file-20210602-17-147g5xw.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/403896/original/file-20210602-17-147g5xw.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Using a microscope to look at thin sections of volcanic rocks.</span>
<span class="attribution"><span class="source">Heather Handley</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>Now let’s take a look through a scanning electron microscope at the border where the mantle crystals make contact with the now-solidified magma.</p>
<p>In the two photos below, you can see the rim of the crystals has become lighter in colour, which means it changed its chemical composition. This is so it could adapt to its new magma environment on ascent in a process called <a href="https://www.nature.com/articles/s43017-020-0038-x">diffusion</a>.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/403970/original/file-20210602-15-1fr3cn7.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/403970/original/file-20210602-15-1fr3cn7.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/403970/original/file-20210602-15-1fr3cn7.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=403&fit=crop&dpr=1 600w, https://images.theconversation.com/files/403970/original/file-20210602-15-1fr3cn7.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=403&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/403970/original/file-20210602-15-1fr3cn7.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=403&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/403970/original/file-20210602-15-1fr3cn7.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=506&fit=crop&dpr=1 754w, https://images.theconversation.com/files/403970/original/file-20210602-15-1fr3cn7.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=506&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/403970/original/file-20210602-15-1fr3cn7.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=506&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The dark grey expanse is the mantle fragment. It has a light coloured rim due to its interaction with the rising magma. On the right, bits of mantle crystals are breaking off.</span>
<span class="attribution"><span class="source">Heather Handley</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/403971/original/file-20210602-13-wk9ucs.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/403971/original/file-20210602-13-wk9ucs.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/403971/original/file-20210602-13-wk9ucs.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=403&fit=crop&dpr=1 600w, https://images.theconversation.com/files/403971/original/file-20210602-13-wk9ucs.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=403&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/403971/original/file-20210602-13-wk9ucs.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=403&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/403971/original/file-20210602-13-wk9ucs.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=506&fit=crop&dpr=1 754w, https://images.theconversation.com/files/403971/original/file-20210602-13-wk9ucs.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=506&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/403971/original/file-20210602-13-wk9ucs.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=506&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">A crystal fragment (130 microns in width) from a peridotite mantle within a volcanic rock from Mount Gambier. The light grey rim has a different chemical composition to the darker area inside.</span>
<span class="attribution"><span class="source">Heather Handley</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>We use the sharpness of this chemical boundary to estimate how long mantle fragments sat in the magma before the rock erupted. </p>
<p>In other words, the minimum time magma took to travel from source to surface — an eruption warning time.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/curious-kids-why-do-volcanoes-erupt-98251">Curious Kids: Why do volcanoes erupt?</a>
</strong>
</em>
</p>
<hr>
<p>I can also use the chemistry and shapes of crystals that grew within the magma itself to map out the plumbing system beneath the volcano — the route magma takes to the surface.</p>
<p>The photos below show some of the different shapes crystals can form as the magma rises to the surface, cooling along the way. The spiky and skeleton-shaped crystals grow when the rising magma cools fast and by a large degree.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/403972/original/file-20210602-23-1ci4mz.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/403972/original/file-20210602-23-1ci4mz.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/403972/original/file-20210602-23-1ci4mz.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=403&fit=crop&dpr=1 600w, https://images.theconversation.com/files/403972/original/file-20210602-23-1ci4mz.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=403&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/403972/original/file-20210602-23-1ci4mz.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=403&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/403972/original/file-20210602-23-1ci4mz.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=506&fit=crop&dpr=1 754w, https://images.theconversation.com/files/403972/original/file-20210602-23-1ci4mz.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=506&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/403972/original/file-20210602-23-1ci4mz.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=506&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The small (5 to 10 microns in size), spikier crystals are clear in this image. The black areas are holes from trapped gas bubbles.</span>
<span class="attribution"><span class="source">Heather Handley</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/403973/original/file-20210602-25-bju3zt.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/403973/original/file-20210602-25-bju3zt.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/403973/original/file-20210602-25-bju3zt.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=403&fit=crop&dpr=1 600w, https://images.theconversation.com/files/403973/original/file-20210602-25-bju3zt.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=403&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/403973/original/file-20210602-25-bju3zt.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=403&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/403973/original/file-20210602-25-bju3zt.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=506&fit=crop&dpr=1 754w, https://images.theconversation.com/files/403973/original/file-20210602-25-bju3zt.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=506&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/403973/original/file-20210602-25-bju3zt.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=506&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Skeleton-shaped olivine crystal in a volcanic rock from Mount Gambier. 500 microns in width.</span>
<span class="attribution"><span class="source">Heather Handley</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/403885/original/file-20210602-17-1l6qhsv.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/403885/original/file-20210602-17-1l6qhsv.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/403885/original/file-20210602-17-1l6qhsv.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=554&fit=crop&dpr=1 600w, https://images.theconversation.com/files/403885/original/file-20210602-17-1l6qhsv.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=554&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/403885/original/file-20210602-17-1l6qhsv.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=554&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/403885/original/file-20210602-17-1l6qhsv.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=696&fit=crop&dpr=1 754w, https://images.theconversation.com/files/403885/original/file-20210602-17-1l6qhsv.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=696&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/403885/original/file-20210602-17-1l6qhsv.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=696&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The same volcanic crystal, but through a regular microscope.</span>
<span class="attribution"><span class="source">Heather Handley</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>And we’re finding so far that individual volcanoes in the Newer Volcanics Province can take strikingly different pathways to the surface. This could result in varying eruption warning times. </p>
<h2>Australia isn’t prepared</h2>
<p>With likely maximum warning times of some past eruptions in Australia on the order of days, it’s worth considering how prepared we are for future eruptions — and not just from within Australia. If the global pandemic has taught us anything, it’s to expect the unexpected. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/403895/original/file-20210602-13-rn6nr8.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/403895/original/file-20210602-13-rn6nr8.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/403895/original/file-20210602-13-rn6nr8.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/403895/original/file-20210602-13-rn6nr8.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/403895/original/file-20210602-13-rn6nr8.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/403895/original/file-20210602-13-rn6nr8.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/403895/original/file-20210602-13-rn6nr8.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/403895/original/file-20210602-13-rn6nr8.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Microscopic view of a mantle fragment brought to the surface during a volcanic eruption at Mount Quincan in the Atherton Volcanic Province, Queensland.</span>
<span class="attribution"><span class="source">Heather Handley</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/403892/original/file-20210602-27-rd0lyo.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/403892/original/file-20210602-27-rd0lyo.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/403892/original/file-20210602-27-rd0lyo.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/403892/original/file-20210602-27-rd0lyo.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/403892/original/file-20210602-27-rd0lyo.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/403892/original/file-20210602-27-rd0lyo.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/403892/original/file-20210602-27-rd0lyo.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/403892/original/file-20210602-27-rd0lyo.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">A mantle fragment from Mount Quincan in the Atherton Volcanic Province, Queensland.</span>
<span class="attribution"><span class="source">Heather Handley</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>Large volcanic events are far from recent human memory, but in the Asia-Pacific region, they occur with a frequency of around every <a href="https://www.asiainsurancereview.com/Magazine/ReadMagazineArticle?aid=35311">400 years</a>. </p>
<p>The federal government’s recent announcement of <a href="https://www.pm.gov.au/media/helping-communities-rebuild-and-recover-natural-disasters">A$600 million</a> towards establishing a new National Recovery and Resilience Agency will help Australia adapt to some climate change-associated hazards. But volcanic events appear to be excluded.</p>
<p>Preparing for the next potentially cataclysmic volcanic event in Australia’s neighbouring <a href="https://www.nationalgeographic.org/article/plate-tectonics-ring-fire/?utm_source=BibblioRCM_Row">Ring of Fire</a> should be part of Australia’s risk and resilience conversation.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/the-government-has-pledged-over-800m-to-fight-natural-disasters-it-could-be-revolutionary-if-done-right-160348">The government has pledged over $800m to fight natural disasters. It could be revolutionary — if done right</a>
</strong>
</em>
</p>
<hr>
<img src="https://counter.theconversation.com/content/161176/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Heather Handley receives funding from the Australian Research Council. Heather is a General Governing Councillor of the Geological Society of Australia and Co-Founder and President of the Women in Earth and Environmental Science Australasia (WOMEESA) Network. She is a 2021-2022 Science and Technology Australia Superstar of STEM.</span></em></p>I look at fragments of the Earth’s mantle under a microscope to learn how fast molten rock moves from deep in the Earth to the surface. This can help us prepare for future volcanic eruptions.Heather Handley, Honorary Associate Professor in Volcanology and Geochemistry, Macquarie UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1593622021-04-21T08:39:21Z2021-04-21T08:39:21ZThe St Vincent eruption is a reminder of how volcano research and monitoring can save lives<p>Volcanic eruptions come with a variety of hazards, depending on the type of volcano and its magma. Some have effusive eruptions, where lava flows constantly, while others can expel large clouds of fragments of magma and gases – volcanic ash – into the atmosphere. </p>
<p>For some of the most powerful eruptions, these ash clouds can rise tens of kilometres into the air and travel thousands of kilometres. This is what has happened on the island of St Vincent and the Grenadines, after a new eruption was confirmed at La Soufrière volcano on April 9 2021.</p>
<p>The explosive eruption, the first since the volcano last erupted in 1979, produced an ash plume of about six kilometres, which was also seen <a href="https://landsat.gsfc.nasa.gov/landsat-8/operational-land-imager">in satellite images</a>. </p>
<p>The eruption prompted the evacuation of about 20,000 people, with no casualties. This was made possible thanks to our improved understanding of how volcanoes work and new advances in volcano monitoring. </p>
<p>What’s different about the eruption in St Vincent compared with the relatively quiet and tourist-friendly eruptions at the same time in <a href="https://www.bbc.co.uk/news/world-europe-56482798">Iceland</a>, is that the magma is much more viscous – or sticky – so the gases dissolved in it can’t easily escape. </p>
<p>As magma moves towards the surface, these gases form bubbles and try to expand, causing an increase in pressure, which can eventually produce an explosion. During explosive eruptions, magma is broken into pieces, which cool rapidly and are ejected from volcanic vents mixed with gases, forming an ash-rich volcanic plume.</p>
<figure class="align-center ">
<img alt="Satellite images of the La Soufriere volcano." src="https://images.theconversation.com/files/396034/original/file-20210420-21-1g2bo2w.jpg?ixlib=rb-1.1.0&rect=105%2C346%2C2155%2C1557&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/396034/original/file-20210420-21-1g2bo2w.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=547&fit=crop&dpr=1 600w, https://images.theconversation.com/files/396034/original/file-20210420-21-1g2bo2w.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=547&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/396034/original/file-20210420-21-1g2bo2w.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=547&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/396034/original/file-20210420-21-1g2bo2w.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=687&fit=crop&dpr=1 754w, https://images.theconversation.com/files/396034/original/file-20210420-21-1g2bo2w.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=687&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/396034/original/file-20210420-21-1g2bo2w.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=687&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Satellite image of the ash.</span>
<span class="attribution"><a class="source" href="https://appliedsciences.nasa.gov/our-impact/news/eruption-la-soufriere">NASA/Lauren Dauphin</a></span>
</figcaption>
</figure>
<p>The island of St Vincent is no stranger to the hazards posed by volcanoes, although it’s been over 40 years since the last explosive eruption of La Soufrière. The deadliest eruption from this volcano occurred from 1902 to 1903 when more than 1,600 people lost their lives. </p>
<p>The current eruption is being monitored by a team of scientists from the University of the West Indies, based at the Belmont Volcano Observatory, on St Vincent. Monitoring relies on various methods, including gas and seismic measurements, as well as observations from the ground and from satellites. Satellites help, for instance, track where the volcanic ash has travelled to.</p>
<h2>Volcanic plumbing</h2>
<p>All volcanic eruptions are fed by a “plumbing system”. This comprises magma-filled cracks, called dykes and sills, that are either created or used by the magma. Understanding the physics that control how volcanic plumbing systems are created and evolve is fundamental to accurately interpret the indirect signals of magma movement.</p>
<p>As the magma moves within the volcano, it deforms the surrounding rock. This can produce earthquakes, which can be located using seismometers and very small deformation of the Earth’s surface, which GPS devices or satellites are able to measure.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/magma-refills-could-predict-volcano-eruptions-16212">Magma refills could predict volcano eruptions</a>
</strong>
</em>
</p>
<hr>
<p>Research conducted in modelling laboratories uses a scaled-down model of the Earth’s crust and simulates magma moving through it. By using a transparent crust, we can see inside the volcano’s plumbing system and create a model volcano monitoring network using <a href="https://www.sciencedirect.com/science/article/pii/S0377027317304602">lasers</a>. </p>
<p>This set-up can be used to test how well data from real volcanoes might be interpreted, helping to understand important information such as where the magma is, how deep it is, how much magma might be erupted, and where and when an eruption might happen.</p>
<p>Based on recent observations, scientists have noticed that immediately before an eruption, the signals of magma movement <a href="https://www.frontiersin.org/articles/10.3389/feart.2018.00045/full">can go quiet</a>. This “quieting down” might be wrongly interpreted as the system going back to sleep, when in fact it might suggest an eruption is imminent. These uncertainties made volcano monitoring and hazard assessment especially difficult.</p>
<h2>Monitoring volcanoes</h2>
<p>Eruptions can happen suddenly, with little or no warning. Mitigating volcanic hazards depends on our ability to continuously measure the pulse of a volcano and assess its state of health – by measuring things like how much magma is being transferred into the crust and how its migration towards the surface. </p>
<p>In many respects, these efforts are similar to how doctors attempt to diagnose a condition in a patient based on their symptoms. Magma moving through the system is akin to blood moving through the body, feeding and nurturing the growing volcano.</p>
<p>There have been many advances over the past few decades meaning more data – collected as often as once every hundredth of a second – is being collected at active volcanoes. New methods are being developed that allow rapid and reliable assessment of the state of a volcano, in some cases revealing clear patterns in the <a href="https://www.frontiersin.org/articles/10.3389/feart.2020.00169/full">lead-up to eruptions</a>.</p>
<p>We know the style and intensity of eruptions are <a href="https://www.sciencedirect.com/book/9780123859389/the-encyclopedia-of-volcanoes">controlled by factors</a> that include magma composition and gas content, the tectonic environment, and the dynamics of magma migration. </p>
<p>Volcano monitoring and our ability to forecast eruptions remain incomplete. However, the eruption in St Vincent demonstrates the role of data interpretation. Getting better at forecasting eruptions is key to successfully inform risk mitigation efforts during volcanic crises, and so prevent loss of life. </p>
<p>A challenging task for the future will be to distil this ever-growing body of knowledge and translate it into new monitoring tools to inform volcano early warning and, possibly, to produce reliable forecasts.</p><img src="https://counter.theconversation.com/content/159362/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Silvio De Angelis receives funding from the Natural Environment Research Council. </span></em></p><p class="fine-print"><em><span>Janine Kavanagh receives funding from a UK Research and Innovation (UKRI) Future Leaders Fellowship. </span></em></p>The eruption prompted the evacuation of about 20,000 people, with no casualties.Silvio De Angelis, Reader in Geophysics, University of LiverpoolJanine Kavanagh, Senior Lecturer in Volcanology and UKRI Future Leaders Fellow, University of LiverpoolLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1568992021-03-12T19:00:29Z2021-03-12T19:00:29ZEarth’s early magma oceans detected in 3.7 billion year-old Greenland rocks<figure><img src="https://images.theconversation.com/files/389271/original/file-20210312-13-1o4pbk9.jpg?ixlib=rb-1.1.0&rect=10%2C0%2C7252%2C4845&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">4 billion years ago, the Earth was composed of a series of magma oceans hundreds of kilometres deep.</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-illustration/realistic-alien-planet-outer-space-3d-1429607681">Larich/Shutterstock</a></span></figcaption></figure><p>Earth hasn’t always been a blue and green oasis of life in an otherwise inhospitable solar system. During our planet’s first 50 million years, around 4.5 billion years ago, its surface was a hellscape of magma oceans, bubbling and belching with heat from Earth’s interior.</p>
<p>The subsequent cooling of the planet from this molten state, and the crystallisation of these magma oceans into solid rock, was <a href="https://www.nature.com/articles/nature06355">a defining stage</a> in the assembly of our planet’s structure, the chemistry of its surface, and the formation of its early atmosphere.</p>
<p>These primeval rocks, containing clues that might explain Earth’s habitability, were assumed to have been lost to the ravages of plate tectonics. But now, <a href="http://dx.doi.org/10.1126/sciadv.abc7394">my team has discovered</a> the chemical remnants of Earth’s magma oceans in 3.7 billion year-old rocks from southern Greenland, revealing a tantalising snapshot of a time when the Earth was almost entirely molten.</p>
<h2>Hell on Earth</h2>
<p>Earth is the product of a chaotic early solar system, which is believed to have featured a number of catastrophic impacts between the Earth and other planetary bodies. The formation of Earth culminated in <a href="https://www.nature.com/articles/35089010">its collision with a Mars-sized impactor planet</a>, which also resulted in the formation of Earth’s moon some 4.5 billion years ago.</p>
<p>These cosmic clashes are thought to have generated enough energy to melt the Earth’s crust and almost all of our planet’s interior (the mantle), creating planetary-scale volumes of molten rock that formed “magma oceans” hundreds of kilometres in depth. Today, in contrast, Earth’s crust is entirely solid, and the mantle is seen as a “plastic solid”: allowing slow, viscous geological movement a far cry from the liquid magma of Earth’s early mantle.</p>
<p>As the Earth recovered and cooled after its chaotic collisions, its deep magma oceans <a href="https://www.sciencedirect.com/science/article/pii/S0012821X19305771">crystallised and solidified</a>, beginning Earth’s journey to the planet we know today. The volcanic gases which bubbled out of Earth’s cooling magma oceans may have been decisive in the formation and composition of our planet’s early atmosphere – which would eventually support life. </p>
<figure class="align-center ">
<img alt="The Earth's layers in a cross-section, showing the core, mantle, and crust" src="https://images.theconversation.com/files/389270/original/file-20210312-20-8ptx8n.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/389270/original/file-20210312-20-8ptx8n.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=398&fit=crop&dpr=1 600w, https://images.theconversation.com/files/389270/original/file-20210312-20-8ptx8n.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=398&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/389270/original/file-20210312-20-8ptx8n.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=398&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/389270/original/file-20210312-20-8ptx8n.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=500&fit=crop&dpr=1 754w, https://images.theconversation.com/files/389270/original/file-20210312-20-8ptx8n.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=500&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/389270/original/file-20210312-20-8ptx8n.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=500&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">The Earth is now composed of the inner core, the outer core, the lower mantle, the upper mantle, and the crust.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-illustration/structure-planet-earth-space-3d-rendering-1614442552">AlexLMX/Shutterstock</a></span>
</figcaption>
</figure>
<h2>Geological search</h2>
<p>Finding geological evidence for the Earth’s former molten state is extremely difficult. This is because magma ocean events are likely to have taken place over 4 billion years ago, and many of the rocks from that period of Earth’s history have since been recycled by plate tectonics. </p>
<p>But while rocks from this period no longer exist, their chemical traces may still be stored in Earth’s depths. Solidified crystals from Earth’s cooling period would have been so dense that they’d have sunk to the base of Earth’s mantle. Scientists even believe that these mineral residues may be stored in isolated zones deep within <a href="https://www.sciencedirect.com/science/article/pii/S0012821X19301797">Earth’s mantle-core boundary</a>.</p>
<p>If they do exist, these ancient crystal graveyards are inaccessible to us – hiding far too deep for us to take direct samples. And if they were to ever rise to the Earth’s surface, the magma ocean crystals would naturally undergo a process of melting and solidifying, leaving only traces of their origins in the volcanic rocks that make it to Earth’s crust.</p>
<h2>Crystal clues</h2>
<p>We knew Greenland would be a good place to search for these traces of Earth’s molten past. Our samples originate from the Isua supracrustal belt in southwestern Greenland, which is a <a href="https://royalsocietypublishing.org/doi/10.1098/rsnr.2009.0004">famous area for geologists</a>. At first glance, Isua’s rocks look just like any modern basalt you’d find on the sea floor. But these rocks some of the oldest in the world, believed to be between 3.7 and 3.8 billion years old. </p>
<p>On analysing Isua’s rocks, we discovered unique iron isotope signatures. These signatures showed that the region of the mantle from which the rocks had formed had been subjected to very high pressure, over 700 kilometres below Earth’s surface. That’s exactly where minerals formed during magma ocean crystallisation would have been located. </p>
<p>But if these rocks did indeed bear traces of crystallised magma ocean, how did they find their way to the Earth’s surface? The answer lies in how the Earth’s interior melts, producing volcanic rocks on the planet’s surface.</p>
<h2>Melting rocks</h2>
<p>When regions of the Earth’s semi-solid mantle heat up and melt, they rise buoyantly towards the Earth’s crust, ultimately producing volcanic rocks when the magma reaches the surface and cools. By studying the chemistry of these rocks on the surface, we can probe the composition of the material that melted to form them.</p>
<p>The isotopic makeup of Isua rocks revealed that their journey to Earth’s surface involved several stages of crystallisation and remelting in the interior of the planet – a kind of distillation process on their way to the surface. But the rocks that emerged, located in present-day Greenland, still retain chemical signatures that connect them to Earth’s magma-covered past. </p>
<p>The results of our work provide some of the first direct geological evidence for the signature of magma ocean crystals in volcanic rocks found on Earth’s surface. Now, we’d like to understand whether other ancient volcanic rocks across the world can tell us more about Earth’s former magma oceans, or whether we’ve instead stumbled upon a geological oddity: more of a one-off clue. </p>
<p>If other volcanoes may have spewed similar geological artefacts, we might also look to modern eruption hotspots such as Hawaii and Iceland for further <a href="https://www.pnas.org/content/117/49/30993.short">isotopic novelties</a> that speak of Earth’s ancient past. It’s possible that more primordial rocks may be found in the future which could help us understand more about the Earth’s violent, magma-covered past.</p><img src="https://counter.theconversation.com/content/156899/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Helen M Williams has received funding from NERC and the ERC. </span></em></p>The rocks provide rare evidence of a time when Earth’s surface was a deep sea of incandescent magma.Helen M Williams, Reader in Geochemistry, University of CambridgeLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1251592019-10-30T16:09:39Z2019-10-30T16:09:39ZHow volcanoes recycle the Earth’s crust to uncover rare metals that are vital to green technology<figure><img src="https://images.theconversation.com/files/299465/original/file-20191030-17914-hioyra.png?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">The Motzfeldt deposit in southern Greenland.</span> <span class="attribution"><span class="license">Author provided</span></span></figcaption></figure><p>To understand the resources of the near future, geologists need to understand the volcanoes of the distant past. Exploration of ancient magma chambers in places such as Greenland has the potential to provide new sources of the rare metals that underpin modern green technologies.</p>
<p>Many rare metals – such as <a href="https://www.rsc.org/periodic-table/element/60/neodymium">neodymium</a>, <a href="https://www.rsc.org/periodic-table/element/41/niobium">niobium</a> and <a href="https://www.rsc.org/periodic-table/element/66/dysprosium">dysprosium</a> – essential to the production of wind turbines and electric cars, are mined from fossil volcanoes.</p>
<p>Volcanoes are nature’s way of bringing material from deep within the earth up to the surface. Melting processes within the <a href="https://www.nationalgeographic.org/encyclopedia/mantle/">mantle</a> – the interior part of the Earth between the super-heated core and the thin outer crust – produce magma which rises up hundreds of kilometres and eventually erupts on to the surface as volcanoes.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/16zt7x1Z9Fs?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
</figure>
<p>The earth’s crust is made up of semi-rigid <a href="https://theconversation.com/how-earths-continents-became-twisted-and-contorted-over-millions-of-years-116168">tectonic plates</a> which move around and collide to form mountains or sink underneath one another at regions called <a href="https://www.universetoday.com/43822/subduction-zone/">subduction zones</a>. The volume of material brought to the Earth’s surface by volcanoes is balanced by similar amounts of material going back into the mantle via sinking tectonic plates. </p>
<p>This points to what we call “element cycles”, where material from depth comes up to the surface via volcanoes and then returns again to the mantle via subduction. One of the big questions in Earth Sciences is what happens to this subducted material and how long it resides in the mantle.</p>
<h2>Fossil volcanoes</h2>
<p>Our recent <a href="https://www.nature.com/articles/s41467-019-12218-1">research</a> studied a group of ancient volcanoes in southern Greenland. Around 1.3 billion years ago, Greenland was a volcanic landscape with deep rift valleys much like modern East Africa. <a href="https://www.sciencedirect.com/science/article/pii/S0012821X1830089X">Substantial volcanoes erupted</a> on to the land surface and major river systems similar to the Nile carried minerals from these volcanoes over huge areas.</p>
<p>The rivers and volcanoes in Greenland are now long eroded, but the <a href="https://www.cambridge.org/core/journals/geological-magazine/article/age-hf-isotope-and-trace-element-signatures-of-detrital-zircons-in-the-mesoproterozoic-eriksfjord-sandstone-southern-greenland-are-detrital-zircons-reliable-guides-to-sedimentary-provenance-and-timing-of-deposition/D0C436D308724096242DDF2E7F89B0C9">sediments</a> that the river transported can still be found, and the volcanic “plumbing systems” that operated beneath these ancient volcanoes have preserved samples of the magmas that erupted.</p>
<p>We wanted to understand how element cycling relates to the concentration of critical metals in these ancient volcanoes in Greenland. While it is useful to study the valuable elements themselves, sometimes we can learn more about Earth’s element cycles by studying other elements associated with them. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/299479/original/file-20191030-17868-v4vrl3.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/299479/original/file-20191030-17868-v4vrl3.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=214&fit=crop&dpr=1 600w, https://images.theconversation.com/files/299479/original/file-20191030-17868-v4vrl3.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=214&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/299479/original/file-20191030-17868-v4vrl3.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=214&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/299479/original/file-20191030-17868-v4vrl3.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=269&fit=crop&dpr=1 754w, https://images.theconversation.com/files/299479/original/file-20191030-17868-v4vrl3.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=269&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/299479/original/file-20191030-17868-v4vrl3.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=269&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Fentale volcano in the Ethiopian rift has erupted large volumes of chemically evolved magma similar to Greenland.</span>
<span class="attribution"><span class="license">Author provided</span></span>
</figcaption>
</figure>
<h2>Fingerprinting sulphur</h2>
<p>In our study we used the element sulphur of which there are four stable forms (called <a href="https://www.sciencealert.com/explainer-what-is-an-isotope">isotopes</a>). Each has a slightly different mass. This is important because natural processes can selectively separate lighter isotopes from heavier isotopes. Much like snacking on a bag of M&M’s where you prefer the red ones and leave behind the brown M&Ms, geological processes lead to variations in the relative abundances of each element in different materials.</p>
<p>By measuring the amount of isotope in rocks, we can learn about the processes that formed them. Sulphur isotopes are particularly useful because bio- and geochemical processes on the Earth’s surface (at low temperatures) are very efficient at <a href="https://www.nature.com/articles/ngeo1585">modifying</a> sulphur signatures, whereas magmatic processes (at high temperatures) do not create much variation between light and heavy sulphur. </p>
<p>So the variations in sulphur signatures in magmatic rocks allow us to fingerprint traces of recycled crustal material in the mantle source. By choosing volcanoes that were active at different periods of geological time, we reconstruct how the mantle composition and sulphur cycling have varied over Earth’s history.</p>
<p>Geologists have known for a long time that Earth’s surface has changed profoundly over the past 4.5 billion years as life emerged and became progressively more complex. The <a href="https://www.nature.com/articles/ngeo1585">increasing imprint of life on the sulphur cycle</a> has dramatically changed the sulphur isotope ratio of sediments at the surface of the Earth, but this imprint has not previously been documented in rocks from the mantle.</p>
<p>Our work shows for the first time that the sulphur signature of the Earth’s mantle changed in a manner that broadly matches the changes in sulphur on the Earth’s surface. Biological and atmospheric impacts on the surface sulphur signature appear to have been transferred all the way into the Earth’s interior.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/299528/original/file-20191030-17878-6lu3mj.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/299528/original/file-20191030-17878-6lu3mj.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=380&fit=crop&dpr=1 600w, https://images.theconversation.com/files/299528/original/file-20191030-17878-6lu3mj.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=380&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/299528/original/file-20191030-17878-6lu3mj.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=380&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/299528/original/file-20191030-17878-6lu3mj.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=477&fit=crop&dpr=1 754w, https://images.theconversation.com/files/299528/original/file-20191030-17878-6lu3mj.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=477&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/299528/original/file-20191030-17878-6lu3mj.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=477&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption"></span>
<span class="attribution"><span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>This means that the Earth’s surface and mantle are strongly connected – one responding to changes in the other – although timescales of this recycling remain unknown. Our data show that sulphur that was once on the Earth’s surface went back into the mantle through tectonic plate activity and then – 1.3 billion years ago – found itself coming back to the surface in the Greenland volcanoes. It’s like geological <em>déjà-vu</em>.</p>
<h2>One cycle or many?</h2>
<p>How many times has sulphur been recycled between the Earth’s crust and mantle over geological time? We do not currently know the answer to this but our research paints a picture of the Earth as a global element conveyor belt with surface sulphur and mantle closely linked. </p>
<p>The study has many implications. A major question in geology is how rare metal deposits form, particularly the <a href="https://www.worldbank.org/en/topic/extractiveindustries/brief/climate-smart-mining-minerals-for-climate-action">high-tech metals</a> that are essential for the green energy revolution. The story from sulphur seems to be consistent with our work on other isotopes. For example, one of the world’s biggest deposits of the element <a href="https://www.rsc.org/periodic-table/element/73/tantalum">tantalum</a> (used in electronics and also concentrated in one of the ancient volcanoes in Greenland) has isotopic fingerprints that also <a href="https://www.sciencedirect.com/science/article/pii/S0169136819300988">hint at crustal recycling</a>.</p>
<p>It may be that these global cycles have taken elements from surface to mantle and back again many times, effectively concentrating those elements each time. The global cycle that we have documented in sulphur may be an essential precursor to generate the metal deposits that are crucial to modern technologies. By understanding plate tectonics and magmatic processes that took place billions of years ago, we gain insights into how to identify and understand the mineral resources of the future.</p><img src="https://counter.theconversation.com/content/125159/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Adrian Finch receives funding from NERC consortium grant NE/M010856/1 for SoS RARE and the EU Horizon 2020 fund for HiTech AlkCarb grant agreement no. 689909.
In addition to the formal authors in the article, Adrian Finch's research group also includes Nicola Horsburgh and Krzysztof Sokół who also contributed to the backdrop of understanding metal resources on which the article draws. His colleague Eva Stüeken assisted with the sulphur modelling used in the Hutchison et al. (2019) article. </span></em></p><p class="fine-print"><em><span>Anouk Borst receives funding from NERC consortium grant NE/M010856/1 for SoS RARE and Global Challenges Research Funding from the Scottish Funding Council.</span></em></p><p class="fine-print"><em><span>William Hutchison receives funding from the European Union’s Horizon 2020 research and innovation programme and a UKRI Future Leaders Fellowship.</span></em></p>Exploration of ancient magma chambers in fossil volcanoes has the potential to provide new sources of metals that will facilitate environmentally friendly technologies.Adrian Finch, Professor of Geology, School of Earth & Environmental Sciences, University of St AndrewsDr Anouk M Borst, Research Fellow Geology, University of St AndrewsWilliam Hutchison, Research Fellow, University of St AndrewsLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1146962019-06-24T12:47:41Z2019-06-24T12:47:41ZWe probed Santorini’s volcano with sound to learn what’s going on beneath the surface<figure><img src="https://images.theconversation.com/files/273695/original/file-20190509-183083-li2utt.jpg?ixlib=rb-1.1.0&rect=0%2C9%2C2285%2C1358&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Sound waves let researchers visualize what's happening below the surface.</span> <span class="attribution"><span class="source">Emilie Hooft</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span></figcaption></figure><p>The island of Santorini in the Mediterranean has attracted people for millennia. Today, it feels magical to watch the sun set from cliffs over the deep bay, surrounded by cobalt blue churches and whitewashed houses. This mystical place attracts about 2 million tourists per year, making it one of the <a href="https://www.planetware.com/tourist-attractions/greece-gr.htm">top destinations in Greece</a>.</p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/280752/original/file-20190621-61751-g0nt87.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/280752/original/file-20190621-61751-g0nt87.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/280752/original/file-20190621-61751-g0nt87.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=620&fit=crop&dpr=1 600w, https://images.theconversation.com/files/280752/original/file-20190621-61751-g0nt87.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=620&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/280752/original/file-20190621-61751-g0nt87.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=620&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/280752/original/file-20190621-61751-g0nt87.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=779&fit=crop&dpr=1 754w, https://images.theconversation.com/files/280752/original/file-20190621-61751-g0nt87.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=779&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/280752/original/file-20190621-61751-g0nt87.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=779&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The Greek islands of Santorini form the perimeter of a volcano whose last major explosion happened about 3,400 years ago. Now the center of the crater-like caldera is filled with seawater.</span>
<span class="attribution"><a class="source" href="https://photojournal.jpl.nasa.gov/catalog/PIA02673">NASA/GSFC/METI/ERSDAC/JAROS and U.S./Japan ASTER Science Team</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<p>Not all those visitors recognize that Santorini is an active volcano. In 1630 B.C., the volcano exploded and collapsed leaving behind an almost circular hole. This is the caldera – visible today as a bay filled with seawater and lined by cliffs. The large explosion <a href="https://archaeology-travel.com/greece/south-aegean/santorini/akrotiri/">covered a Bronze Age town</a>, burying buildings in volcanic ash two stories deep. </p>
<p>The <a href="https://www.arcgis.com/apps/MapJournal/index.html?appid=007b8ebcbfe34bfabf17c486b2445637">latest lava flows erupted in 1950</a> and <a href="https://www.volcanodiscovery.com/santorini/1950-eruption.html">expanded the islands that have grown at the center of the caldera</a>. Recently, in 2011-2012, the volcano went through a period of unrest. The ground bulged up and out, and many small earthquakes occurred. <a href="https://news.nationalgeographic.com/news/2012/09/120912-magma-balloon-lava-santorini-volcano-science/">Scientists concluded</a> that a small amount of magma was injected about 2.5 miles (4 kilometers) under the northern portion of the caldera.</p>
<p>What attracted me to this iconic place is that most of the volcano is submerged under water. <a href="https://scholar.google.com/citations?user=GoO8Z7oAAAAJ&hl=en&oi=ao">I am a geophysicist</a> interested in how magma moves deep in the Earth. Over the past decade, I’ve been <a href="https://youtu.be/LXh8lZK55VE">using advanced technology</a> to improve how we “see” magma’s otherwise hidden pathways below volcanoes around the world.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/sygEQzn0BP4?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Get a glimpse of how researchers conducted their seismic experiment to understand the volcano of Santorini.</span></figcaption>
</figure>
<h2>Using sound to see what’s beneath the surface</h2>
<p>In the 1780s, French scientist Ferdinand Fouquet traveled to Santorini to view an ongoing eruption. He was the first to realize how the volcanic <a href="https://www.nationalgeographic.org/encyclopedia/caldera/">surface depression known as a caldera was formed</a>. As magma emptied out of its underground reservoir during the eruption, the roof of rock that had been covering it collapsed. The flanks of the volcano that remained form the ring of islands visible above water today.</p>
<p>My research project aimed to delve deeper, literally, than <a href="https://doi.org/10.1016/j.tecto.2017.06.005">what we can see from the surface</a> to figure out what’s going on within this still active volcano. A blanket of water over everything except the very top of the Santorini volcano meant I could use deep-penetrating marine sound sources to “illuminate” the subsurface structures. My international collaborators and I wanted to find the location and depth where magma was collecting and how much magma there is right now.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/273678/original/file-20190509-183086-5rgr4p.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/273678/original/file-20190509-183086-5rgr4p.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/273678/original/file-20190509-183086-5rgr4p.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=268&fit=crop&dpr=1 600w, https://images.theconversation.com/files/273678/original/file-20190509-183086-5rgr4p.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=268&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/273678/original/file-20190509-183086-5rgr4p.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=268&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/273678/original/file-20190509-183086-5rgr4p.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=337&fit=crop&dpr=1 754w, https://images.theconversation.com/files/273678/original/file-20190509-183086-5rgr4p.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=337&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/273678/original/file-20190509-183086-5rgr4p.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=337&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">R/V Marcus Langseth within the Santorini caldera with an ocean-bottom seismometer floating in front of the ship.</span>
<span class="attribution"><span class="source">Doug Toomey</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<p>We conducted our work from the R/V Marcus Langseth, an American marine seismic ship. It is the only academic ship with a sound source capable of imaging the deep insides of a volcano. This technology is controversial because of the <a href="https://doi.org/10.1038/460939b">potential impact of loud sounds</a> on marine wildlife and its intensive use by oil exploration companies.</p>
<p>We spent months doing environmental permitting and finding the optimal design for the experiment. <a href="https://santorini.uoregon.edu">The ship carried a team</a> of experienced biological observers who surveyed the sea both above and below water for sound-sensitive or endangered species. If any were observed at a distance, we were to follow a prescribed set of actions to ensure they wouldn’t be disturbed. After all this preparation, though, we saw almost no wildlife during the expedition.</p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/280802/original/file-20190621-61747-175xtok.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/280802/original/file-20190621-61747-175xtok.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/280802/original/file-20190621-61747-175xtok.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=459&fit=crop&dpr=1 600w, https://images.theconversation.com/files/280802/original/file-20190621-61747-175xtok.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=459&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/280802/original/file-20190621-61747-175xtok.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=459&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/280802/original/file-20190621-61747-175xtok.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=577&fit=crop&dpr=1 754w, https://images.theconversation.com/files/280802/original/file-20190621-61747-175xtok.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=577&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/280802/original/file-20190621-61747-175xtok.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=577&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">One of the airguns. It has a volume of 180 cubic inches and is about 18 inches long.</span>
<span class="attribution"><span class="source">Emilie Hooft</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<p>Our “active source seismic imaging” method is like making a CAT-scan picture of the inside of the Earth. Instead of building an image using X-rays, though, we use sound waves generated by 36 heavy, metal canisters – called airguns – that are towed deep in the water behind the ship. When the airguns open, compressed air pushes on the seawater, creating a sound wave that travels through the Earth.</p>
<p>In this instance, the sound travels through the rocks beneath the volcano. Then seismic sensors resting on the seafloor on the other side of the volcano record when the sound reaches them. The team installed 65 of these stations on land, across Santorini and the nearby islands, and dropped another 90 stations to the seafloor. </p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/273702/original/file-20190509-183109-l65l0a.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/273702/original/file-20190509-183109-l65l0a.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/273702/original/file-20190509-183109-l65l0a.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/273702/original/file-20190509-183109-l65l0a.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/273702/original/file-20190509-183109-l65l0a.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/273702/original/file-20190509-183109-l65l0a.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/273702/original/file-20190509-183109-l65l0a.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/273702/original/file-20190509-183109-l65l0a.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The team installing one of the land seismometers on Anafi.</span>
<span class="attribution"><span class="source">Joanna Morgan, Imperial College London</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<p>We have to use very accurate timing to measure how long it takes the sound energy to go through the different parts of the volcano. The energy from the sound source will travel more slowly through rocks that are broken or that are hot and contain magma. When we probe the structure from many different directions and at many different depths, we can recover a detailed picture of the interior of the Earth.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/273681/original/file-20190509-183106-3expvj.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/273681/original/file-20190509-183106-3expvj.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/273681/original/file-20190509-183106-3expvj.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=311&fit=crop&dpr=1 600w, https://images.theconversation.com/files/273681/original/file-20190509-183106-3expvj.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=311&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/273681/original/file-20190509-183106-3expvj.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=311&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/273681/original/file-20190509-183106-3expvj.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=391&fit=crop&dpr=1 754w, https://images.theconversation.com/files/273681/original/file-20190509-183106-3expvj.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=391&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/273681/original/file-20190509-183106-3expvj.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=391&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">University of Oregon graduate student Brandon VanderBeek capturing an ocean-bottom seismometer after it resurfaces. The caldera cliffs of Santorini are in the distance. The black fresh lavas of the island inside the caldera are in front, on the left.</span>
<span class="attribution"><span class="source">Emilie Hooft</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<p>To get the data back from the seafloor, we send a special sound signal to the sensor – like a bird call – that commands the instrument to drop its anchor. Then everyone scans the sea looking for the instrument. During the day we search for a cheerful orange flag, at night a strobe light makes this task easier. Our ship maneuvers alongside the instrument and a crew member leans over the side, hooks the instrument on a long pole and pulls it back on board. The data is in hand. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/273696/original/file-20190509-183112-yzuwdz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/273696/original/file-20190509-183112-yzuwdz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/273696/original/file-20190509-183112-yzuwdz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=371&fit=crop&dpr=1 600w, https://images.theconversation.com/files/273696/original/file-20190509-183112-yzuwdz.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=371&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/273696/original/file-20190509-183112-yzuwdz.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=371&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/273696/original/file-20190509-183112-yzuwdz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=467&fit=crop&dpr=1 754w, https://images.theconversation.com/files/273696/original/file-20190509-183112-yzuwdz.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=467&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/273696/original/file-20190509-183112-yzuwdz.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=467&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Scientists gather around the map table in the R/V Langseth’s main laboratory.</span>
<span class="attribution"><span class="source">PROTEUS Science Team</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<h2>Filling out the subsurface picture</h2>
<p>Analysis of the seismic data is an enormous task. It required experienced inspection by Ph.D. student Ben Heath and master’s student Brennah McVey. We then used seismic tomography to make the first detailed “photographs” of Santorini’s subsurface structure. The term tomography comes from the Greek words “tomos” for slice and “graphos” for draw. Basically sophisticated computer code makes a three-dimensional digital model of the object of interest based on the speed sound waves traveled through it.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/280795/original/file-20190621-61733-1wgf0d7.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/280795/original/file-20190621-61733-1wgf0d7.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/280795/original/file-20190621-61733-1wgf0d7.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=329&fit=crop&dpr=1 600w, https://images.theconversation.com/files/280795/original/file-20190621-61733-1wgf0d7.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=329&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/280795/original/file-20190621-61733-1wgf0d7.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=329&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/280795/original/file-20190621-61733-1wgf0d7.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=413&fit=crop&dpr=1 754w, https://images.theconversation.com/files/280795/original/file-20190621-61733-1wgf0d7.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=413&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/280795/original/file-20190621-61733-1wgf0d7.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=413&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The grey volume is the column of porous rock beneath the northern caldera. This is the zone of the initial collapse during the Bronze age eruption. As the plumbing system refills, magma (red in this schematic) accumulates directly beneath this region.</span>
<span class="attribution"><span class="source">Brennah McVey, University of Oregon</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<p>Surprisingly, <a href="https://doi.org/10.1016/j.epsl.2019.02.033">we found a narrow zone of collapsed rock</a> hiding within the broad caldera at Santorini. <a href="http://elementsmagazine.org/2019/06/11/late-bronze-age-eruption-santorini-volcano-impact-ancient-mediterranean-world/">Geological studies</a> of the eruptions at Santorini hadn’t led us to expect there would be a confined volume of rocks in the northern part of the caldera that sound traveled through more slowly. Rather we thought the entire caldera would be filled with this type of broken rock at shallow depths. Our finding meant that the collapsed portion of the caldera was much narrower and deeper than it appears from the surface. </p>
<p>This column of disrupted rock is less than 2 miles (3 km) across – small compared to the size of the 6-mile-wide (10 km) caldera. The structure goes down into the ground 2 miles (3 km) below the bottom of the bay. These rocks must contain lots of water-filled gaps to have sufficiently slowed the seismic energy we recorded.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/vJqmypD17mU?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">3D visualization of Santorini’s caldera and magma plumbing system.</span></figcaption>
</figure>
<p>To figure out how this unique volume of disrupted rock formed, we drew on existing knowledge of <a href="https://nom.maps.arcgis.com/apps/Cascade/index.html?appid=2a6c54875bf743dd8143786a55dcb2b1">Santorini’s most recent large explosion</a>, the Late Bronze Age eruption in 1630 B.C. As magma erupted from the subsurface, it caused the overlying rocks to break up. At the same time, underground explosions fractured the rocks when magma and water came into contact. Then, above this collapsing column, the seafloor depression filled with porous volcanic deposits from the eruption itself. Finally, the entire bay dropped down and <a href="https://doi.org/10.1038/ncomms13332">rapid flooding formed a tsunami wave</a>.</p>
<p>What is particularly interesting about our findings is that magma continues to accumulate directly beneath the column of disrupted rock – thousands of years after the explosion that originally created the caldera. My colleagues and I think the rising magma comes to a halt beneath the reduced weight of the broken rock in the collapsed column.</p>
<p>Our research helps explain how magma systems are reset and regrow after major volcanic episodes.</p><img src="https://counter.theconversation.com/content/114696/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Emilie Hooft receives funding from the U.S. National Science Foundation. The experiment and analysis were supported by National Science Foundation grant number OCE-1459794 to the University of Oregon and Leverhulme Grant RPG-2015-363 to Imperial College London. Data used in this research were provided by instruments from the Ocean Bottom Seismograph Instrument Pool, which is funded by the National Science Foundation. The Geophysical Instrument Pool Potsdam provided 60 land seismometers. The Aristotle University of Thessaloniki contributed 5 land seismometers and the Greek military donated helicopter time for installations on the smaller islands. This work benefited from access to the University of Oregon high performance computer, Talapas. </span></em></p>Geophysicists use sound waves to build a picture of the magma and rock beneath this active volcano, most of which is underwater. It’s like CT scanning the Earth.Emilie Hooft, Associate Professor of Earth Sciences, Volcanology Cluster of Excellence, & Oregon Hazards Lab, University of OregonLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1170052019-05-21T19:40:28Z2019-05-21T19:40:28ZThe ‘pulse’ of a volcano can be used to help predict its next eruption<figure><img src="https://images.theconversation.com/files/274836/original/file-20190516-69178-x4wstq.jpg?ixlib=rb-1.1.0&rect=0%2C645%2C4031%2C2372&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">The 2018 eruption of Kilauea volcano was preceded by damage of the magma plumbing system at the summit.</span> <span class="attribution"><span class="source">Courtesy of Grace Tobin, 60 Minutes</span>, <span class="license">Author provided</span></span></figcaption></figure><p>Predicting when a volcano will next blow is tricky business, but <a href="https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2018GL081609" title="Decrease in Seismic Velocity Observed Prior to the 2018 Eruption of Kīlauea Volcano With Ambient Seismic Noise Interferometry">lessons we learned</a> from one of Hawaii’s recent eruptions may help.</p>
<p><a href="https://theconversation.com/au/topics/kilauea-53358">Kīlauea</a>, on the Big Island of Hawai'i, is probably the best understood volcano on Earth. That’s thanks to monitoring and gathered information that extends back to the formation of the <a href="https://volcanoes.usgs.gov/observatories/hvo/">Hawaiian Volcano Observatory</a> in 1912.</p>
<p>The volcano is also subject to the world’s most technologically advanced geophysical monitoring network.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/from-kilauea-to-fuego-three-things-you-should-know-about-volcano-risk-97775">From Kilauea to Fuego: three things you should know about volcano risk</a>
</strong>
</em>
</p>
<hr>
<p>From the skies, satellites collect data that show the changing topography of the volcano as magma moves throughout the internal magma plumbing system. Satellites also look at the composition of volcanic gases. </p>
<p>From the ground, volcanologists use a number of highly sensitive chemical and physical tools to further understand the structure of that magma plumbing system. This helps to study the movement of magma within the volcano.</p>
<h2>Earthquakes and vibrations</h2>
<p>A lynch pin of volcano monitoring is seismicity – how often, where and when earthquakes occur. Magma movement within the volcano triggers earthquakes, and putting together the data on their location (a technique known as triangulation) tracks the path of magma underground.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/274839/original/file-20190516-69178-wpysqy.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/274839/original/file-20190516-69178-wpysqy.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/274839/original/file-20190516-69178-wpysqy.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=215&fit=crop&dpr=1 600w, https://images.theconversation.com/files/274839/original/file-20190516-69178-wpysqy.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=215&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/274839/original/file-20190516-69178-wpysqy.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=215&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/274839/original/file-20190516-69178-wpysqy.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=271&fit=crop&dpr=1 754w, https://images.theconversation.com/files/274839/original/file-20190516-69178-wpysqy.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=271&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/274839/original/file-20190516-69178-wpysqy.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=271&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">A schematic of the deep magma plumbind system of Kilauea volcano, Big Island, Hawaii. Magma is transported from deep within the Earth and arrives in a series of summit magma reservoirs.</span>
<span class="attribution"><span class="source">USGS</span></span>
</figcaption>
</figure>
<p>A newer technique, seismic interferometry, uses vibrations of energy from ocean waves hitting the distant shorelines that then travel through the volcano.</p>
<p>Changes in the speed of these vibrations help us map the 3D footprint of the volcano’s magma plumbing system. We can then detect when, and in some cases how, the magma plumbing system is changing.</p>
<p>This monitoring provides the “pulse” of the volcano during times of inactivity - a baseline from which to detect change during volcanic unrest. This proved invaluable for early warning, and the prediction of where and when, of the eruption of Kīlauea on May 3, 2018.</p>
<p>The “pulse” of Kīlauea includes cycles of <a href="https://volcanoes.usgs.gov/observatories/hvo/hvo_volcano_watch.html?vwid=117">volcano inflation (bulging) and deflation (contraction)</a> as magma moves into and out of the storage region at the summit of the volcano.</p>
<p>The speeds of vibrations travelling through the volcano are predictable during observations of inflation/deflation cycles. When the volcano bulges, the vibrations travel faster through the volcano as rock and magma is compressed. When the volcano contracts these speeds decrease.</p>
<p>We describe this relationship between the two sets of data – the bulging/contraction and the faster/slower speed of vibrations – as coupled.</p>
<h2>Something changed</h2>
<p>Compared to our baseline, we saw the coupled data shift 10 days before the Kīlauea eruption on May 3. That told scientists the magma plumbing system had changed in a significant way.</p>
<p>The volcano was bulging due to the buildup of pressure inside the magma chamber, but the seismic waves were slowing down quite dramatically, instead of speeding up. </p>
<p>Our interpretation of this data was that the summit magma chamber was not able to sustain the pressure from an increasing magma supply – the bulge was too big. Rock material started to break around the summit magma chamber.</p>
<p>Breakage of the rocks perhaps then led to changes of the summit magmatic system so that more magma could more easily arrive at the eruption site about 40km away.</p>
<p>As well as Kīlauea, such coupled data sets are regularly collected, investigated and interpreted in terms of magma transport at other volcanoes globally. Sites include Piton de la Fournaise on Reunion Island, and Etna volcano, Italy. </p>
<p>But our <a href="https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2018GL081609">modelling</a> was the first to demonstrate these changes in the coupled data relationship could occur due to weakening of the material inside the volcano before an eruption.</p>
<p>The damage model that we applied can now be used for other volcanoes in a state of unrest. This adds to the toolbox volcanologists need to predict the when and where of an impending eruption. </p>
<h2>So much data, we need help</h2>
<p>When volcanoes are in a heightened state of unrest, the volume of information available from digital data and ground observations is extreme. Scientists tend to rely on observational monitoring first, and other data when time and extra people are available. </p>
<p>But the total amount of incoming data (such as from satellites) is overwhelming, and scientists simply can’t keep up. Machine learning might be able to help us here. </p>
<p><a href="https://www.sciencemag.org/news/2018/12/artificial-intelligence-helps-predict-volcanic-eruptions">Artificial intelligence</a> is the new kid on the block for eruption prediction. Neural networks and other algorithms can use high volumes of complex data and “learn” to distinguish between different signals.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/how-the-dinosaurs-went-extinct-asteroid-collision-triggered-potentially-deadly-volcanic-eruptions-112134">How the dinosaurs went extinct: asteroid collision triggered potentially deadly volcanic eruptions</a>
</strong>
</em>
</p>
<hr>
<p><a href="https://www.nature.com/articles/d41586-018-07420-y">Automated early alert systems</a> of an impending eruption using sensor arrays exist for some volcanoes today, for example at Etna volcano, Italy. It’s likely that artificial intelligence will make these systems more sophisticated in the future.</p>
<p>Early detection sounds wonderful for authorities charged with public safety, but many volcanologists are wary.</p>
<p>If they lead to multiple false alarms then that could slash trust in scientists for both managers of volcanic crises and the public alike.</p><img src="https://counter.theconversation.com/content/117005/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Rebecca Carey receives funding from the Australian Research Council, US National Science Foundation and New Zealand Marsden Grant.</span></em></p>Scientists say they’ve found a new method to help predict when volcanoes will erupt, based on data crunched from an eruption last year in Hawaii.Rebecca Carey, Senior Lecturer in Earth Sciences, University of TasmaniaLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/998312018-08-09T05:08:51Z2018-08-09T05:08:51ZI’ve Always Wondered: Why are the volcanoes on Earth active, but the ones on Mars are not?<p><em>This is an article from I’ve Always Wondered, a series where readers send in questions they’d like an expert to answer. Send your question to alwayswondered@theconversation.edu.au</em></p>
<hr>
<p><strong>I’ve always wondered why we still have active volcanoes on Earth but those of Mars stopped millions of years ago. What’s the difference between the planets that explains this? – Nial, Sydney</strong> </p>
<p>Volcanoes have been an important part of the history of both Earth and Mars. So why do we not <a href="https://theconversation.com/monster-volcanoes-on-mars-how-space-rocks-are-helping-us-solve-their-mysteries-85045">see any activity on Mars today?</a></p>
<p>The quick answer is because Mars is smaller than our planet. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/discovered-a-huge-liquid-water-lake-beneath-the-southern-pole-of-mars-100523">Discovered: a huge liquid water lake beneath the southern pole of Mars</a>
</strong>
</em>
</p>
<hr>
<h2>Twice as high as Everest</h2>
<p>Olympus Mons is one of the largest mountains in the solar system – it dwarfs all of the mountains on Earth. It sits on the surface of Mars and dominates the landscape. </p>
<p>As long ago as the 19th century observers like <a href="https://www.nasa.gov/audience/forstudents/postsecondary/features/F_Canali_and_First_Martians.html">Schiaparelli</a> had noted that the top of Olympus Mons could sit above the red planet’s frequent dust storms. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/229774/original/file-20180730-106502-gvvmy5.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/229774/original/file-20180730-106502-gvvmy5.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=154&fit=crop&dpr=1 600w, https://images.theconversation.com/files/229774/original/file-20180730-106502-gvvmy5.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=154&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/229774/original/file-20180730-106502-gvvmy5.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=154&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/229774/original/file-20180730-106502-gvvmy5.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=194&fit=crop&dpr=1 754w, https://images.theconversation.com/files/229774/original/file-20180730-106502-gvvmy5.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=194&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/229774/original/file-20180730-106502-gvvmy5.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=194&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Olympus Mons is way higher and wider than even Mt Everest and the Himalayas.</span>
<span class="attribution"><a class="source" href="https://commons.wikimedia.org/wiki/File:Olympus_Mons_Side_View.svg">Wikimedia Commons</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<p>Olympus Mons is just one of <a href="http://solarviews.com/eng/marsvolc.htm">thousands of volcanoes </a> observed on the surface of Mars, and we know that volcanic activity has shaped the majority of the planet’s surface. </p>
<p>But this is a process that has long since stopped on that planet: the youngest volcanoes on Mars are about 500 million years old. That’s before dinosaurs roamed the Earth.</p>
<p>The lack of currently active volcanoes on Mars is quite puzzling, given we see evidence that volcanoes were active there up from 3.7 billion years ago to 500 million years ago.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/228114/original/file-20180717-44079-7oj0cl.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/228114/original/file-20180717-44079-7oj0cl.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/228114/original/file-20180717-44079-7oj0cl.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/228114/original/file-20180717-44079-7oj0cl.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/228114/original/file-20180717-44079-7oj0cl.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/228114/original/file-20180717-44079-7oj0cl.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/228114/original/file-20180717-44079-7oj0cl.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Olympus Mons is an extinct volcano on Mars.</span>
<span class="attribution"><a class="source" href="https://svs.gsfc.nasa.gov/1094">A visualisation by Tom Bridgman/NASA</a></span>
</figcaption>
</figure>
<h2>It’s about gravity</h2>
<p>Both Earth and Mars are terrestrial planets, mostly made up of rock and metal.</p>
<p>But Mars only has a tenth of the mass of Earth. This has a profound effect on gravity: if you weigh 100 kg on Earth you’ll only weigh 38 Kg on Mars.</p>
<p>Low gravity has a dramatic effect on how volcanic eruptions can take place on Mars, as these are driven by buoyancy of the fluid rock, known as magma. </p>
<p>Magma is a really complicated mixture of liquid, solid and gas components, and changes frequently as it moves about a planet’s subsurface. Buoyancy is the contrast in density between the surrounding crust rock and the magma ascending for eruption. A high buoyancy means that the magma comes to the surface quite easily. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/230851/original/file-20180807-160647-15u5260.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/230851/original/file-20180807-160647-15u5260.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=399&fit=crop&dpr=1 600w, https://images.theconversation.com/files/230851/original/file-20180807-160647-15u5260.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=399&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/230851/original/file-20180807-160647-15u5260.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=399&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/230851/original/file-20180807-160647-15u5260.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=501&fit=crop&dpr=1 754w, https://images.theconversation.com/files/230851/original/file-20180807-160647-15u5260.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=501&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/230851/original/file-20180807-160647-15u5260.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=501&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Buoyant magma comes to the surface easily.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/lava-flow-hawaii-volcano-national-park-99208310">from www.shutterstock.com</a></span>
</figcaption>
</figure>
<p>On Mars, the buoyancy of magma is relatively low, and the gravity is also relatively low. Also, the magma chambers that feed the eruptions are deeper than their counterparts on Earth. All up, this means more “oomph” is required to overcome the lower magma buoyancy and bring it to the surface of the planet. We think this leads to bigger but less frequent eruptions on Mars. </p>
<p>These bigger eruptions might explain how Olympus Mons got so big. Bigger eruptions mean more magma delivered to the surface, which is more material to build a monster mountain. </p>
<h2>Heat energy also matters</h2>
<p>While Mars’ gravity probably leads to bigger and less frequent eruptions, this doesn’t necessarily explain why we don’t see anything active today. Many believe this could be because this smaller planet has simply lost most of its heat energy. </p>
<p>A terrestrial planet has two main ways of generating heat: radioactive decay and primordial heating. </p>
<p>The <a href="https://www.nde-ed.org/EducationResources/HighSchool/Radiography/radioactivedecay.htm">radioactive decay</a> comes from elements like potassium and uranium, which although present in small amounts, can release a lot of energy throughout the planet. <a href="http://www.sciencemag.org/news/2011/07/earth-still-retains-much-its-original-heat">Primordial heating</a> is from the first formation of a planet – in the case of Mars as a mixture of metal and rock, where energy has come from the denser metal sinking towards the core. </p>
<p>While on Earth these two heat <a href="https://earthobservatory.sg/seismology/why-interior-earth-hot">sources are going strong</a>, this may not be the case for Mars. As a smaller planet it would have had less radiogenic and primordial heat sources to start with, so the planet may have already cooled down too much to drive volcanic activity. </p>
<p>However, we now know of other much smaller bodies – such as <a href="https://theconversation.com/jupiters-new-moons-an-irregular-bunch-with-an-extra-oddball-thats-the-smallest-discovered-so-far-100160">Jupiter’s moon Io</a> and <a href="https://theconversation.com/what-cassinis-mission-revealed-about-saturns-known-and-newly-discovered-moons-83430">Saturn’s moon Enceladus</a> – that are volcanically active. This (at least in Io’s case) is driven by tidal forces generated by their close orbit to a gas giant. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/230852/original/file-20180807-191031-1ue1b7f.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/230852/original/file-20180807-191031-1ue1b7f.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=647&fit=crop&dpr=1 600w, https://images.theconversation.com/files/230852/original/file-20180807-191031-1ue1b7f.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=647&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/230852/original/file-20180807-191031-1ue1b7f.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=647&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/230852/original/file-20180807-191031-1ue1b7f.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=813&fit=crop&dpr=1 754w, https://images.theconversation.com/files/230852/original/file-20180807-191031-1ue1b7f.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=813&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/230852/original/file-20180807-191031-1ue1b7f.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=813&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">NASA’s InSight mission will measure seismic activity on Mars – which could come from magma moving under the surface.</span>
<span class="attribution"><a class="source" href="https://www.nasa.gov/jpl/pia19811/artists-concept-of-insight-lander-on-mars">NASA/JPL-Caltech</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<h2>Evidence incoming</h2>
<p>But new sources of evidence do arise. </p>
<p>The European Space Agency’s Mars Express mission has spotted what was interpreted to be a <a href="https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/2011GL047310">more recent lava flow</a> (only a mere two million years old) on Mars. </p>
<p>And with NASA’s <a href="https://mars.nasa.gov/insight/">InSight mission</a>, currently on its way to the red planet, we could potentially catch volcanic activity in the act. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/launching-in-may-the-insight-mission-will-measure-marsquakes-to-explore-the-interior-of-mars-91080">Launching in May, the InSight mission will measure marsquakes to explore the interior of Mars</a>
</strong>
</em>
</p>
<hr>
<p>If all goes well, the InSight probe will sit on the Martian surface and listen for seismic activity (sound waves travelling through the rock). Seismic activity on Mars could be due to meteorite impacts or marsquakes, but it could also result from magma moving through the crust.</p><img src="https://counter.theconversation.com/content/99831/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Helen Maynard-Casely does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>Compared to Earth, more “oomph” is required to bring magma to the surface of Mars, and this is probably why we haven’t seen any recent eruptions on the red planet.Helen Maynard-Casely, Instrument Scientist, Australian Nuclear Science and Technology OrganisationLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/977752018-06-06T00:43:13Z2018-06-06T00:43:13ZFrom Kilauea to Fuego: three things you should know about volcano risk<p>Recent photographs and video from the <a href="https://theconversation.com/fuego-volcano-the-deadly-pyroclastic-flows-that-have-killed-dozens-in-guatemala-97707">devastating eruption</a> of Fuego volcano in Guatemala show people stood watching and filming hot, cloud-like flows of gas, ash and volcanic material (known as <a href="https://volcanoes.usgs.gov/vhp/pyroclastic_flows.html">pyroclastic flows</a>) travelling towards them down the slopes of the volcano. </p>
<p><div data-react-class="Tweet" data-react-props="{"tweetId":"1003414675986567168"}"></div></p>
<p>From this it is clear that some people do not fully understand the risks of the volcanoes they live near. </p>
<p>Although <a href="https://www.britannica.com/science/volcano">each volcano is different</a>, and each presents different risks to the people near to them, there are some generalisations that help us understand what these risks are likely to be.</p>
<p>Three points are clear: location matters, explosiveness can be predicted to an extent, and fast-moving pyroclastic flows of volcanic material are deadly. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/fuego-volcano-the-deadly-pyroclastic-flows-that-have-killed-dozens-in-guatemala-97707">Fuego volcano: the deadly pyroclastic flows that have killed dozens in Guatemala</a>
</strong>
</em>
</p>
<hr>
<h2>1. Location matters</h2>
<p>The outer layer of the Earth, called the <a href="https://www.nationalgeographic.org/encyclopedia/lithosphere/">lithosphere</a> (crust and upper mantle), is broken up into a number of rigid tectonic plates. <a href="http://geologylearn.blogspot.com/2016/03/relation-of-volcanism-to-plate-tectonics.html">Volcanoes typically occur</a> where the plates move apart from one another, for example at underwater mid-ocean ridges, or collide together at subduction zones. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/221706/original/file-20180605-175438-d1ydm6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/221706/original/file-20180605-175438-d1ydm6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/221706/original/file-20180605-175438-d1ydm6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=337&fit=crop&dpr=1 600w, https://images.theconversation.com/files/221706/original/file-20180605-175438-d1ydm6.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=337&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/221706/original/file-20180605-175438-d1ydm6.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=337&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/221706/original/file-20180605-175438-d1ydm6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=423&fit=crop&dpr=1 754w, https://images.theconversation.com/files/221706/original/file-20180605-175438-d1ydm6.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=423&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/221706/original/file-20180605-175438-d1ydm6.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=423&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Australia sits in the middle of a tectonic plate - whereas New Zealand sits on a boundary between two tectonic plates. <strong>CLICK ON IMAGE TO ZOOM</strong></span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-vector/plate-tectonics-earths-lithosphere-scientific-theory-134705048?src=tTw-S8Bbu7hIuslxFGjmZg-1-4">from www.shutterstock.com</a></span>
</figcaption>
</figure>
<p>We also find volcanoes in the middle of tectonic plates – these are called “intraplate” volcanoes, such as the Hawaiian and Galápagos oceanic islands. </p>
<p>The magma (molten rock) that feeds volcanoes is generated in different ways in these settings, and different volcanic landforms result. </p>
<p>Hawaii is in the middle of a tectonic plate and volcanic activity there forms relatively low-profile, <a href="https://volcano.si.edu/learn_galleries.cfm?p=2">shield volcanoes</a>. Typically, these volcanoes are built up by many fluid lava flows into broad, gently sloping domes, which resemble a warrior’s shield.</p>
<p>In contrast, Fuego is situated in a subduction zone environment (one plate going under another) where steep-sided, <a href="http://volcano.oregonstate.edu/stratovolcanoes">stratovolcanoes, or composite</a> volcanoes are most common. These often symmetrical, conical volcanoes form from the build up of layers of lava and pyroclastic (fragmented volcanic) rocks.</p>
<h2>2. Magma and gas affect explosiveness</h2>
<p>The volcanic landforms and eruptive styles we see in different settings are largely a <a href="http://www.geology.sdsu.edu/how_volcanoes_work/Controls.html">result of the differences</a> in the composition of the magma (molten rock) erupted, its temperature and its gas content in these contrasting tectonic settings.</p>
<p>Large shield volcanoes in the middle of tectonic plates, such as <a href="https://volcanoes.usgs.gov/volcanoes/kilauea/geo_hist_2008.html">Kilauea volcano in Hawaii</a>, erupts high temperature, low silica lava. This is runnier (less viscous) than magma typically erupted at subduction zone volcanoes (like Fuego). </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/eruptions-and-lava-flows-on-kilauea-but-whats-going-on-beneath-hawaiis-volcano-96919">Eruptions and lava flows on Kilauea: but what's going on beneath Hawai'i's volcano?</a>
</strong>
</em>
</p>
<hr>
<p>This means that any volatiles (dissolved gases such as water, carbon dioxide and sulphur dioxide) in the Kilauea magma are able to escape more easily compared to in a stickier, higher silica, magma that characterises subduction zone volcanoes.</p>
<p>And so “Hawaiian-style” eruptions are characterised by lava fountaining and flows of hot fluid lava that normally travel slow enough for people to walk away from and evacuate. This is exactly what we have been seeing over the last month in Kilauea’s East Rift Zone.</p>
<p><div data-react-class="Tweet" data-react-props="{"tweetId":"998032498259996674"}"></div></p>
<p>In contrast, at subduction zone volcanoes – such as Fuego – the higher water content of the magma and the typically more silica-rich, sticky magmas erupt more explosively. It is harder for gas bubbles formed to escape as magma rises to the surface, which then take up more space and over pressure the system. </p>
<p>Subduction zone volcanoes can produce high columns of gas and ash reaching tens of kilometres into the atmosphere, and scalding hot, fast-moving, cloud-like currents of gas, ash and volcanic material. These pyroclastic flows, or “pyroclastic density currents”, race down the volcano at speeds over 80 km/hr. </p>
<p><div data-react-class="Tweet" data-react-props="{"tweetId":"1004036622604816386"}"></div></p>
<p>Some news reports of eruptions at Fuego have incorrectly termed these pyroclastic flows “rivers of lava”. They are very different to lava flows and much more hazardous. </p>
<p>Clear and accurate communication of volcanic eruptions is crucial if those near the volcano are to understand the real risks.</p>
<h2>3. Pyroclastic flows are deadly</h2>
<p>Pyroclastic flows are extremely hazardous and deadly. They were responsible for deaths in Pompeii and Herculaneum from the AD79 eruption of Vesuvius in Italy. </p>
<p>Even the famous volcanologists <a href="http://volcano.oregonstate.edu/who-were-maurice-and-katia-krafft-how-did-they-die">Katia and Maurice Kraft</a> underestimated the reach of a pyroclastic flow during an eruption at Unzen volcano on June 3, 1991, which killed them along with many others. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/curious-kids-do-most-volcanologists-die-from-getting-too-close-to-volcanoes-82496">Curious Kids: Do most volcanologists die from getting too close to volcanoes?</a>
</strong>
</em>
</p>
<hr>
<p>Historic subduction zone volcanic eruptions producing devastating pyroclastic flows include: </p>
<ul>
<li>Vesuvius, Italy AD 79</li>
<li>Tambora, Indonesia (1815)</li>
<li>Krakatau (Krakatoa), Indonesia (1883)</li>
<li>Mt Pelée, Caribbean (1902)</li>
<li>Mt St Helens, USA (1980)</li>
<li>Mt Pinatubo, Philippines (1991)</li>
<li>Unzen, Japan (1991).</li>
</ul>
<p>At Fuego, the loose, fragmented volcanic material (known as tephra) lying on the slopes after eruptions may be remobilised by rain to form volcanic mudflows known as lahars. These pose a significant current and future risk for the people surrounding Fuego compared to those living in Hawaii. </p>
<p>Pyroclastic density currents were the <a href="https://www.sciencedirect.com/science/article/pii/S0377027305001563">main cause of death from volcanic activity</a> in the 20th Century, killing around 45,000 people, almost 50% of all volcanic deaths in that time period (total deaths from volcanic activity is estimated to be 91,724).</p>
<p>While eyes are diverted toward eruptions in Central America and the Pacific Ocean, <a href="http://www.thejakartapost.com/travel/2018/06/04/alert-statuses-for-19-volcanoes-raised.html">Indonesia has raised the alert level</a> on some of its volcanoes this week. It now has <a href="https://magma.vsi.esdm.go.id/">21 volcanoes</a> on alert levels 2-4 (yellow, orange and red) on a scale of 1-4. </p>
<p>Local authorities will be vital in managing and communicating the risks of these volcanoes, as well as around Fuego and Kilauea.</p><img src="https://counter.theconversation.com/content/97775/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Heather Handley receives funding from the Australian Research Council. </span></em></p>Important points about volcanoes: location matters, explosiveness can be predicted to an extent, and fast-moving flows of volcanic materials (known as pyroclastic flows) are deadly.Heather Handley, Associate Professor in Volcanology and Geochemistry, Macquarie UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/949772018-04-16T20:52:01Z2018-04-16T20:52:01ZHow the Pilbara was formed more than 3 billion years ago<figure><img src="https://images.theconversation.com/files/214906/original/file-20180416-584-12wql9z.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">In the field studying the rock association in the Doolena Gap greenstone belt, 30 km north of Marble bar in the Pilbara region of Western Australia.</span> <span class="attribution"><span class="source">David Murphy</span>, <span class="license">Author provided</span></span></figcaption></figure><p>The remote Pilbara region of northern Western Australia is one of Earth’s oldest blocks of continental crust, and we now think we know how it formed, as explained in research <a href="http://nature.com/articles/doi:10.1038/s41561-018-0105-9">published today in Nature Geoscience</a>.</p>
<p>The region is well known for its rich, ancient Aboriginal history extending over at least 40,000 years. It also features an incredibly diverse ecosystem, with many species found nowhere else.</p>
<p>The architecture of this ancient crust leads to a distinctive landscape as viewed from above, with light-coloured oval features that are granite domes surrounded by dark belts of volcanic and sedimentary rocks, known as greenstone belts.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/target-earth-how-asteroids-made-an-impact-on-australia-92836">Target Earth: how asteroids made an impact on Australia</a>
</strong>
</em>
</p>
<hr>
<p>This unique geological architecture bears witness to the history of our planet.</p>
<iframe src="https://www.google.com/maps/embed?pb=!1m14!1m12!1m3!1d1121615.4829093271!2d118.5212715870071!3d-21.183171415849873!2m3!1f0!2f0!3f0!3m2!1i1024!2i768!4f13.1!5e1!3m2!1sen!2sau!4v1523850308436" width="100%" height="600" frameborder="0" style="border:0" allowfullscreen=""></iframe>
<h2>Billions of years ago</h2>
<p>The Pilbara region began to form more than 3.6 billion years ago and our research supports the idea that its rocks were not formed through the plate tectonics processes that we see in operation today.</p>
<p>In plate tectonics, the outermost layer of Earth consists of fragmented, stiff “tectonic plates” that drift across the planetary surface, interacting at their boundaries. New crust is generated and destroyed at plate boundaries and this process is associated with most of Earth’s current volcanic and earthquake activity. </p>
<p>The plate boundaries are generally composed of fairly straight segments, hundreds of kilometres long. Witness the long chain of volcanoes along South America’s west coast.</p>
<p>So why do the rocks in the Pilbara exhibit this unusual granite-greenstone geometry? </p>
<p>In our <a href="http://nature.com/articles/doi:10.1038/s41561-018-0105-9">research</a> we detail how these rocks formed, describing a series of “gravitational overturn” events that affected the ancient crust in the East Pilbara well before plate-tectonic processes began around 3.2 billion years ago.</p>
<h2>Gravitational overturn</h2>
<p>What is a gravitational overturn? The young Earth was roasting hot. Its large heat content resulted in widespread volcanism. It was too warm for the rigid plates required for plate tectonics to operate.</p>
<p>Imagine retrieving a long-forgotten chocolate bar from your pocket, which then bends and drips over your fingers as you attempt to enjoy a snack. (Modern plates resemble a cold chocolate bar straight from the fridge: it does not bend and breaks when you want a corner.) </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/214934/original/file-20180416-105522-1y0m2u9.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/214934/original/file-20180416-105522-1y0m2u9.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/214934/original/file-20180416-105522-1y0m2u9.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/214934/original/file-20180416-105522-1y0m2u9.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/214934/original/file-20180416-105522-1y0m2u9.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/214934/original/file-20180416-105522-1y0m2u9.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/214934/original/file-20180416-105522-1y0m2u9.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/214934/original/file-20180416-105522-1y0m2u9.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Photograph of at least 3.5 billion year old banded-iron formation showing intensive deformation as a result of gravitational overturn until 3.41 billion years ago.</span>
<span class="attribution"><span class="source">Daniel Wiemer</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>The hot early Earth erupted thick piles of basalt lavas that formed a dense crust barely supported by the underlying mantle. The base of this cooling crust experienced further heating from the hot mantle below until it started to melt, generating relatively buoyant granitic magmas.</p>
<p>This process led to an unstable stratification of the ancient proto-crust: low-density granites were overlain by high-density basalts. Due to the high heat, both layers could bend and flow, leading to instability.</p>
<p>The granitic blobs wanted to rise and the basalts wanted to sink. Scientists call the rising blobs “plumes” and the reorganisation process “gravitational overturn”.</p>
<p>In the early Earth, with its high temperatures and soft crust, the granites rose up through the crust where it formed buoyant stable crust, while most of the dense basalt crust sunk into the mantle. This process is preserved in the Pilbara as the oval-shaped granite domes and the preserved remnants of the basalt crust as the greenstone belts.</p>
<h2>The landscape today</h2>
<p>North of Marble Bar, by looking at rock fabrics, we discovered the remains of the oldest recorded gravitational overturn in the Pilbara. Intensely deformed rocks preserve traces of the ascent of a rising granite plume and the associated down-going of the dense volcanic crust. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/214931/original/file-20180416-127631-3lm0hq.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/214931/original/file-20180416-127631-3lm0hq.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/214931/original/file-20180416-127631-3lm0hq.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/214931/original/file-20180416-127631-3lm0hq.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/214931/original/file-20180416-127631-3lm0hq.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/214931/original/file-20180416-127631-3lm0hq.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/214931/original/file-20180416-127631-3lm0hq.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/214931/original/file-20180416-127631-3lm0hq.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">A rugged landscape formed above the deformed greenstone belts in the Doolena Gap greenstone belt, 30km north of Marble bar.</span>
<span class="attribution"><span class="source">David Murphy</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>Our field observations, geochemical analyses and thermodynamic models demonstrate that rocks collected from the dome margin represent high silica magma that originally melted at a depth of around 42km before crystallising as granites at 20km.</p>
<p>Uranium-lead dating of zircon in the laboratory revealed that these rocks crystallised from 3.6-billion to 3.5 billion years ago.</p>
<p>The intensely sheared rocks at the boundary of the rising dome and sinking volcanic rocks contain a metamorphic mineral, titanite, that formed during the gravitational overturn.</p>
<p>We dated several of these mineral grains and they average 3.42 billion years old.</p>
<p>By dating both pre- and post-gravitational overturn rock associations, we were able to constrain its duration to a 40 million year period.</p>
<p>Combining our research with the published work of <a href="https://doi.org/10.1016/j.epsl.2014.04.025">other</a> <a href="http://sp.lyellcollection.org/content/389/1/1">geologists</a>, it appears that the Pilbara experienced at least three gravitational overturns separated by 100-million-year intervals.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/214938/original/file-20180416-584-1tqbl0k.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/214938/original/file-20180416-584-1tqbl0k.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/214938/original/file-20180416-584-1tqbl0k.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=482&fit=crop&dpr=1 600w, https://images.theconversation.com/files/214938/original/file-20180416-584-1tqbl0k.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=482&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/214938/original/file-20180416-584-1tqbl0k.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=482&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/214938/original/file-20180416-584-1tqbl0k.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=606&fit=crop&dpr=1 754w, https://images.theconversation.com/files/214938/original/file-20180416-584-1tqbl0k.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=606&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/214938/original/file-20180416-584-1tqbl0k.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=606&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Back scatter electron image of titanite taken at Central Analytical Research Facility, QUT. The upper two images are primary magmatic images that have undergone deformation and alteration during the gravitational overturn. The lower two images are metamorphic titanite that formed during the gravitational overturn. The rectangular shapes in the bottom right image are laser pit from the dating process.</span>
<span class="attribution"><span class="source"> Lana Wenham</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>After the final overturn 3.2 billion years ago, the Pilbara crustal block was finally sufficiently robust and buoyant to survive plate tectonics lasting even until today.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/five-active-volcanoes-on-my-asia-pacific-ring-of-fire-watch-list-right-now-90618">Five active volcanoes on my Asia Pacific 'Ring of Fire' watch-list right now</a>
</strong>
</em>
</p>
<hr>
<p>We speculate that the cyclicity of overturn events in the Pilbara is the ancient equivalent of the 500- to 600-million-year <a href="http://www.dictionary.com/browse/wilson-cycle">Wilson cycle</a>, one full round of crust from formation until destruction in the plate tectonic style in existence since 3.2 billion years ago.</p>
<p>The Pilbara keeps inspiring scientists worldwide to finding answers to one of humankind’s great questions: how did nature provide the platform for the eventual evolution of life? </p>
<p>We plan to test the idea of characteristic ancient overturn cycles elsewhere in the Pilbara and on other continents where ancient crust is preserved.</p><img src="https://counter.theconversation.com/content/94977/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Charlotte Allen works for QUT</span></em></p><p class="fine-print"><em><span>Christoph Schrank receives funding from the Australian Research Council. </span></em></p><p class="fine-print"><em><span>Daniel Wiemer and David Murphy do not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and have disclosed no relevant affiliations beyond their academic appointment.</span></em></p>The remote Pilbara region of Western Australian formed many billions of years ago when the Earth was much hotter and the crust softer than it is today.David Murphy, Lecturer in Geoscience, Queensland University of TechnologyCharlotte Allen, Senior Research Officer (Elements & Isotopes), Queensland University of TechnologyChristoph Schrank, Senior Lecturer, Queensland University of TechnologyDaniel Wiemer, Researcher, The University of Western AustraliaLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/910532018-02-07T19:00:46Z2018-02-07T19:00:46ZMore bad news for dinosaurs: Chicxulub meteorite impact triggered global volcanic eruptions on the ocean floor<figure><img src="https://images.theconversation.com/files/205347/original/file-20180207-74479-1ragczb.jpg?ixlib=rb-1.1.0&rect=229%2C0%2C4290%2C3149&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Seismic shockwaves after a meteorite’s collision could affect systems all over the planet.</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-illustration/large-meteor-burning-glowing-hits-earths-488993764">solarseven/Shutterstock.com</a></span></figcaption></figure><p>The end of the Cretaceous period 66 million years ago was a rough time to be living on Earth.</p>
<p>Three global catastrophes occurred nearly simultaneously: The <a href="https://doi.org/10.1126/science.208.4448.1095">Chicxulub meteorite slammed</a> into what is now Mexico’s Yucatan Peninsula, the massive <a href="https://doi.org/10.1038/333843a0">Deccan Traps volcanic province in modern-day India erupted</a>, and some three-quarters of Earth’s plants and animals, including all non-avian dinosaurs, went extinct. The occurrence of these three events at the same time in our planet’s history has fueled a decades-long <a href="https://doi.org/10.1016/S1631-0713(03)00006-3">debate about causal links</a>. Either a large sequence of volcanic eruptions or an extraterrestrial impact could conceivably cause a mass extinction – but were they all somehow connected?</p>
<p>As Earth scientists, we have reason to believe that there may be another event to add to the list. <a href="http://advances.sciencemag.org/content/4/2/eaao2994">Our new research</a>, published in Science Advances, shows that the Chicxulub impact may have triggered additional volcanic activity far from the Deccan Traps – along tens of thousands of miles of undersea volcanic ridges that lie at the edges of tectonic plates. The meteorite impact caused large seismic waves that traveled around the globe and were apparently capable of flushing magma out of the mantle and into the oceanic crust. This would presumably be more bad news for the dinosaurs and other flora and fauna of the time.</p>
<h2>Ripple effects of seismic activity</h2>
<p>It is well known that seismic activity can trigger a variety of hydrologic phenomena, and sometimes even volcanic eruptions. In the aftermath of nearby large earthquakes, <a href="https://doi.org/10.1038/ncomms8597">dry streams can start flowing</a>, well levels can go up or down, and <a href="https://doi.org/10.1146/annurev.earth.34.031405.125125">geysers sometimes erupt</a>. Seismicity also sets off volcanic activity, but only when conditions are just right – it’s only about <a href="https://doi.org/10.1146/annurev.earth.34.031405.125125">0.4 percent of explosive volcanic eruptions</a> that might be triggered by large earthquakes.</p>
<p>So could the massive earthquake generated when the Chicxulub meteorite crashed into Earth be related to the ongoing eruptions in the Deccan Traps? This volcanic province covered much of India with lava flows in less than a million years. A University of California, Berkeley-led team of researchers (including one of us, Leif Karlstrom) <a href="https://doi.org/10.1130/B31167.1">revisited the possibility of a connection</a> between these two events.</p>
<p>The most recent efforts to date these eruptions have clearly shown that the <a href="https://doi.org/10.1126/science.aaa0118">Deccan Traps began spewing lava</a> before the meteorite impact and the mass extinction occurred. But the Berkeley-led study suggested that the <a href="https://doi.org/10.1126/science.aac7549">Chicxulub impact triggered a rapid increase in their eruption rate</a>. If true, all three events could conceivably be connected: The impact would be followed by accelerated volcanic activity that could contribute to the mass extinction.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/205141/original/file-20180206-88775-1vu003i.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/205141/original/file-20180206-88775-1vu003i.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/205141/original/file-20180206-88775-1vu003i.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=338&fit=crop&dpr=1 600w, https://images.theconversation.com/files/205141/original/file-20180206-88775-1vu003i.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=338&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/205141/original/file-20180206-88775-1vu003i.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=338&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/205141/original/file-20180206-88775-1vu003i.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=424&fit=crop&dpr=1 754w, https://images.theconversation.com/files/205141/original/file-20180206-88775-1vu003i.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=424&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/205141/original/file-20180206-88775-1vu003i.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=424&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Underwater lava flows ooze out between tectonic plates, as at Axial Seamount, where it lies on top of older lavas.</span>
<span class="attribution"><span class="source">Bill Chadwick, Oregon State University, and ROV Jason, Woods Hole Oceanographic Institution</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<h2>Looking to the ocean floor</h2>
<p>If the triggering-by-impact hypothesis is right, we’d expect that other volcanic systems would have been set off as well.</p>
<p>At any given time, the vast majority of the volcanic activity on Earth isn’t occurring in continent-covering floods of magma or in explosions like at Mount St. Helens. It’s on the seafloor, where the tectonic plates are spreading apart. As the Earth’s crust splits, the mostly solid mantle layer rises to fill the space created. It melts as it decompresses on the way up.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/205132/original/file-20180206-88799-1rj8m9l.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/205132/original/file-20180206-88799-1rj8m9l.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/205132/original/file-20180206-88799-1rj8m9l.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=203&fit=crop&dpr=1 600w, https://images.theconversation.com/files/205132/original/file-20180206-88799-1rj8m9l.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=203&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/205132/original/file-20180206-88799-1rj8m9l.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=203&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/205132/original/file-20180206-88799-1rj8m9l.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=255&fit=crop&dpr=1 754w, https://images.theconversation.com/files/205132/original/file-20180206-88799-1rj8m9l.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=255&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/205132/original/file-20180206-88799-1rj8m9l.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=255&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Illustration of a mid-ocean ridge, with magma rising from the mantle and erupting through the crust at the boundary between tectonic plates.</span>
<span class="attribution"><span class="source">Background, E. Paul Oberlander, WHOI Graphic Services. Inset, Bill Chadwick, Oregon State University, and ROV Jason, Woods Hole Oceanographic Institution. Modified by Joseph Byrnes</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<p>This new magma percolates its way to the surface and fuels nearly continuous volcanic activity along what are known as <a href="https://en.wikipedia.org/wiki/Mid-ocean_ridge">mid-ocean ridges</a>. This process creates practically all of the crust on the bottom of the ocean. Since the <a href="http://www.earthbyte.org/Resources/agegrid2008.html">ages of the seafloor are relatively well-known</a>, it preserves a record of oceanic volcanic activity stretching back over 100 million years. This remarkable record of volcanic activity creates an opportunity to test the triggering hypothesis.</p>
<p><a href="http://advances.sciencemag.org/content/4/2/eaao2994">In our new study</a>, we used publicly available data sets to make a record of the structure of the seafloor stretching back 100 million years. Since better topographic maps exist for <a href="https://www.jpl.nasa.gov/spaceimages/details.php?id=PIA02820">Mars</a> and <a href="https://sos.noaa.gov/datasets/venus-topography/">Venus</a> than do for the <a href="http://topex.ucsd.edu/marine_topo/">Earth’s seafloor on a global scale</a>, we were forced to use indirect methods to look for variations in seafloor structures.</p>
<p>Minute variations in the strength of gravity at different locations as measured by satellites <a href="http://topex.ucsd.edu/marine_grav/mar_grav.html">provide the requisite mapping tool</a>. Spots that have an excess amount of rock sitting on the seafloor, as you’d expect to result from accelerated volcanic activity, will have a slightly stronger measurement for Earth’s gravitational field.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/205133/original/file-20180206-88775-1s17005.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/205133/original/file-20180206-88775-1s17005.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/205133/original/file-20180206-88775-1s17005.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=298&fit=crop&dpr=1 600w, https://images.theconversation.com/files/205133/original/file-20180206-88775-1s17005.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=298&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/205133/original/file-20180206-88775-1s17005.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=298&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/205133/original/file-20180206-88775-1s17005.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=375&fit=crop&dpr=1 754w, https://images.theconversation.com/files/205133/original/file-20180206-88775-1s17005.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=375&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/205133/original/file-20180206-88775-1s17005.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=375&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The time with the most small structural anomalies on the sea floor – indicating 8 percent more mass anomalies than on average – occurs at 66 million years ago and coincides with the age of the Chicxulub meteorite impact.</span>
<span class="attribution"><span class="source">Byrnes and Karlstrom, Sci. Adv. 2018;4: eaao2994</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<p>We then inspected the record of these “gravity anomalies” to look for any changes to the structure of the seafloor that happened quickly. We found an unusual abundance of these small structural anomalies on the seafloor happened within 1 million years of the Chicxulub impact. The gravity anomalies are consistent with roughly 650 foot high piles of excess material lying on 66-million-year-old seafloor in the Indian and Pacific Oceans.</p>
<p>The total volume of excess material is difficult to pin down, because a large amount of magma could have been injected into the lower crust where it would have a weaker gravitational signature. But we estimate that around the time of the Chicxulub impact, on the order of 23,000 to 230,000 cubic miles of magma erupted out of the mid-ocean ridges, all over the globe. This is on par with the largest eruptive events in Earth’s 4.5-billion-year history, including the Deccan Traps.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/205136/original/file-20180206-88775-1h6n02.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/205136/original/file-20180206-88775-1h6n02.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/205136/original/file-20180206-88775-1h6n02.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=261&fit=crop&dpr=1 600w, https://images.theconversation.com/files/205136/original/file-20180206-88775-1h6n02.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=261&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/205136/original/file-20180206-88775-1h6n02.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=261&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/205136/original/file-20180206-88775-1h6n02.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=327&fit=crop&dpr=1 754w, https://images.theconversation.com/files/205136/original/file-20180206-88775-1h6n02.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=327&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/205136/original/file-20180206-88775-1h6n02.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=327&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Dots mark areas on the seafloor that show high rates of spreading at the time of the Chicxulub impact 66 million years ago. Colors indicate the maximum gravity anomaly within 2 degrees.</span>
<span class="attribution"><span class="source">Byrnes and Karlstrom, Sci. Adv. 2018;4: eaao2994</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<h2>Refining the picture</h2>
<p>Our observations suggest the following sequence of events at the end of the Cretaceous period. Just over 66 million years ago, the Deccan Traps start erupting – likely initiated by a plume of hot rock rising from the Earth’s core, similar in some ways to what’s happening beneath Hawaii or Yellowstone today, that impinged on the side of India’s tectonic plate. The mid-ocean ridges and dinosaurs continue their normal activity.</p>
<p>About 250,000 years later, Chicxulub hits off the coast of what will become Mexico. The impact causes a massive disruption to the Earth’s climate, injecting particles into the atmosphere that will eventually settle into <a href="https://doi.org/10.1126/science.1177265">a layer of clay found across the planet</a>. In the aftermath of impact, volcanic activity accelerates for perhaps tens to hundreds of thousands of years. The mid-ocean ridges erupt large volumes of magma, while the Deccan Traps eruptions flood lava across much of the Indian subcontinent. In the end, three-quarters of the Earth’s plant and animal species have disappeared; the only remaining dinosaurs are the feathered, flying variety, normally referred to as birds. </p>
<p>Now, the goal is to further refine our understanding of each event and their interactions. Was there enough mid-ocean ridge activity to contribute to the mass extinction, or was the triggered submarine volcanism merely a symptom of some more significant planetary ailment? Were other volcanic systems triggered by the Chicxulub impact? Which played a larger role in driving the extinction: the volcanism or the meteor?</p>
<p>What is clear is that this new research points to global-scale connections between catastrophes, a good reminder that events happening on the other side of the planet can have effects felt everywhere.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/8wy33t0U1DE?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Massive eruption of magma may have contributed to mass extinction at the end of the Cretaceous.</span></figcaption>
</figure><img src="https://counter.theconversation.com/content/91053/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Leif Karlstrom receives funding from the National Science Foundation.</span></em></p><p class="fine-print"><em><span>Joseph Byrnes does not work for, consult, own shares in or receive funding from any company or organization that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>Research suggests a new threat to life on Earth from the meteorite’s crash: Via seismic waves, the impact triggered massive undersea eruptions, as big as any ever seen in our planet’s history.Leif Karlstrom, Assistant Professor of Earth Sciences, University of OregonJoseph Byrnes, Postdoctoral Associate of Earth Sciences, University of MinnesotaLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/865662017-11-01T13:36:30Z2017-11-01T13:36:30ZHow to turn a volcano into a power station – with a little help from satellites<figure><img src="https://images.theconversation.com/files/192679/original/file-20171031-18735-1gapo0c.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Erta Ale in eastern Ethiopia.</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/erta-ale-shield-volcano-eastern-ethiopia-651968962?src=qtB_MW4J7_7YV2kH-EHpZw-1-65">mbrand85</a></span></figcaption></figure><p>Ethiopia tends to conjure images of sprawling dusty deserts, bustling streets in Addis Ababa or the precipitous cliffs of the <a href="https://www.simienmountainsnationalpark.org/">Simien Mountains</a> – possibly with a distance runner bounding along in the background. Yet the country is also one of the most volcanically active on Earth, thanks to Africa’s <a href="http://www.nationalgeographic.com.au/videos/geologic-journey/african-rift-the-great-rift-valley-1301.aspx">Great Rift Valley</a>, which runs right through its heart. </p>
<p>Rifting is the geological process that rips tectonic plates apart, roughly at the speed your fingernails grow. In Ethiopia this has enabled magma to force its way to the surface, and there are over 60 known volcanoes. Many have undergone colossal eruptions in the past, leaving behind immense craters that pepper the rift floor. Some volcanoes are still active today. Visit them and you find bubbling mud ponds, hot springs and scores of steaming vents. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/192438/original/file-20171030-18725-yn0y3a.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/192438/original/file-20171030-18725-yn0y3a.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/192438/original/file-20171030-18725-yn0y3a.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=354&fit=crop&dpr=1 600w, https://images.theconversation.com/files/192438/original/file-20171030-18725-yn0y3a.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=354&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/192438/original/file-20171030-18725-yn0y3a.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=354&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/192438/original/file-20171030-18725-yn0y3a.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=445&fit=crop&dpr=1 754w, https://images.theconversation.com/files/192438/original/file-20171030-18725-yn0y3a.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=445&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/192438/original/file-20171030-18725-yn0y3a.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=445&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Steam rising at Aluto volcano, Ethiopia.</span>
<span class="attribution"><span class="source">William Hutchison</span></span>
</figcaption>
</figure>
<p>This steam has been used by locals for washing and bathing, but underlying this is a much bigger opportunity. The surface activity suggests extremely hot fluids deep below, perhaps up to 300°C–400°C. Drill down and it should be possible access this high temperature steam, which could drive large turbines and produce huge amounts of power. This matters greatly in a <a href="https://www.iea.org/publications/freepublications/publication/WEO2014.pdf">country where</a> 77% of the population has no access to electricity, one of the lowest levels in Africa. </p>
<p>Geothermal power has recently become a serious proposition thanks to geophysical surveys <a href="http://www.rg.is/static/files/about-us/rg-corbettigeothermalpower.pdf">suggesting that</a> some volcanoes could yield a gigawatt of power. That’s the <a href="https://energy.gov/eere/articles/how-much-power-1-gigawatt">equivalent of</a> several million solar panels or 500 wind turbines from each. The total untapped resource is <a href="http://theargeo.org/fullpapers/COUNTRY%20UPDATE%20ON%20GEOTHERMAL%20EXPLORATION%20AND%20DEVELOPMENT%20IN%20ETHIOPIA.pdf">estimated to be</a> in the region of 10GW. </p>
<p>Converting this energy into power would build on the geothermal pilot project that began some 20 years ago at Aluto volcano in the lakes region 200km south of Addis Ababa. Its infrastructure is currently being upgraded to increase production tenfold, from 7MW to 70MW. In sum, geothermal looks like a fantastic low-carbon renewable solution for Ethiopia that could form the backbone of the power sector and help lift people out of poverty. </p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/z5sdGyKqtkA?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
</figure>
<h2>Scratching the surface</h2>
<p>The major problem is that, unlike more developed geothermal economies like Iceland, very little is known about Ethiopia’s volcanoes. In almost all cases, we don’t even know when the last eruption took place – a vital question since erupting volcanoes and large-scale power generation will not make happy bedfellows. </p>
<p>In recent years, the UK’s Natural Environment Research Council (NERC) has been funding <a href="https://www.geos.ed.ac.uk/riftvolc/ProjectRiftVolc.html">RiftVolc</a>, a consortium of British and Ethiopian universities and geological surveys, to address some of these issues. This has focused on understanding the hazards and developing methods for exploring and monitoring the volcanoes so that they can be exploited safely and sustainably. </p>
<p>Teams of scientists have been out in the field for the past three years deploying monitoring equipment and making observations. Yet some of the most important breakthroughs have come through an entirely different route – through researchers analysing satellite images at their desks. </p>
<p>This has produced exciting findings at Aluto. Using a satellite radar technique, we <a href="http://onlinelibrary.wiley.com/doi/10.1002/2016GC006395/full">discovered that</a> the volcano’s surface is <a href="http://www.esa.int/Our_Activities/Observing_the_Earth/Highlights/Africa_s_ups_and_downs#">inflating and deflating</a>. The best analogy is breathing – we found sharp “inhalations” inflating the surface over a few months, followed by gradual “exhalations” which cause slow subsidence over many years. We’re not exactly sure what is causing these ups and downs, but it is good evidence that magma, geothermal waters or gases are moving around in the depths some five km below the surface. </p>
<h2>Taking the temperature</h2>
<p>In our <a href="http://www.sciencedirect.com/science/article/pii/S037702731730118X">most recent paper</a>, we used satellite thermal images to probe the emissions of Aluto’s steam vents in more detail. We found that the locations where gases were escaping often coincided with known fault lines and fractures on the volcano. </p>
<p>When we monitored the temperature of these vents over several years, we were surprised to find that most were quite stable. Only a few vents on the eastern margin showed measurable temperature changes. And crucially, this was not happening in synchronicity with Aluto’s ups and downs – we might have expected that surface temperatures would increase following a period of inflation, as hot fluids rise up from the belly of the volcano.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/192440/original/file-20171030-18700-1tm2a02.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/192440/original/file-20171030-18700-1tm2a02.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/192440/original/file-20171030-18700-1tm2a02.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=362&fit=crop&dpr=1 600w, https://images.theconversation.com/files/192440/original/file-20171030-18700-1tm2a02.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=362&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/192440/original/file-20171030-18700-1tm2a02.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=362&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/192440/original/file-20171030-18700-1tm2a02.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=455&fit=crop&dpr=1 754w, https://images.theconversation.com/files/192440/original/file-20171030-18700-1tm2a02.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=455&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/192440/original/file-20171030-18700-1tm2a02.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=455&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">A productive geothermal well on Aluto.</span>
<span class="attribution"><span class="source">William Hutchison</span></span>
</figcaption>
</figure>
<p>It was only when we delved into the rainfall records that we came up with an explanation: the vents that show variations appear to be changing as a delayed response to rainfall on the higher ground of the rift margin. Our conclusion was that the vents nearer the centre of the volcano were not perturbed by rainfall and thus represent a better sample of the hottest waters in the geothermal reservoir. This obviously makes a difference when it comes to planning where to drill wells and build power stations on the volcano, but there’s a much wider significance. </p>
<p>This is one of the first times anyone has monitored a geothermal resource from space, and it demonstrates what can be achieved. Since the satellite data is freely available, it represents an inexpensive and risk-free way of assessing geothermal potential. </p>
<p>With similar volcanoes scattered across countries like Kenya, Tanzania and Uganda, the technique could allow us to discover and monitor new untapped geothermal resources in the Rift Valley as well as around the world. When you zoom back and look at the big picture, it is amazing what starts to come into view.</p><img src="https://counter.theconversation.com/content/86566/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>William Hutchison receives funding from the NERC and from the European Union’s Horizon 2020 research and innovation programme.</span></em></p><p class="fine-print"><em><span>Juliet Biggs receives funding from the NERC. </span></em></p><p class="fine-print"><em><span>Tamsin Mather receives funding from the NERC. </span></em></p>Satellite research in Ethiopia is opening up a new frontier in the hunt for geothermal power.William Hutchison, Research Fellow, University of St AndrewsJuliet Biggs, Reader in Earth Sciences, University of BristolTamsin Mather, Professor of Earth Sciences, University of OxfordLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/783632017-05-30T12:32:56Z2017-05-30T12:32:56ZVenus has very few volcanoes – weirdly, this might be why it’s as hot as hell<figure><img src="https://images.theconversation.com/files/171352/original/file-20170529-25201-1hlmaaj.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-illustration/3d-renderingvenus-resolution-best-quality-solar-580798888?src=cvbKNLlwMuWNBXqY1Qi-cg-3-90">MAX3D</a></span></figcaption></figure><p>In the quest to discover habitable planets, scientists look for qualities similar to those of Earth. We do this because Earth sustains life, of course, but it falls down when you consider Venus. Based on size, chemistry and position in the solar system, our neighbouring planet is the most Earth-like ever observed. Yet while Earth is the definition of habitable, the planet Venus is a barren, hot, hellish wasteland. </p>
<p>Geologists like myself are trying to understand why two almost identical planets became so different. This is one way we can assist the astrophysics community in the exciting hunt for habitable exoplanets. A key part of the puzzle is understanding the interplay between plate tectonics and volcanoes, since <a href="https://theconversation.com/how-the-air-we-breathe-was-created-by-earths-tectonic-plates-33278">this governs</a> the <a href="https://www.nature.com/ngeo/journal/v10/n5/full/ngeo2939.html">chemistry</a> of the air that supports life. </p>
<p>I have been part of a research collaboration to look at Venus’ volcanic history, the results of which have <a href="http://www.sciencedirect.com/science/article/pii/S0031920116301418">just been published</a> in the journal Physics of the Earth and Planetary Interiors. This study sheds some valuable light on the volcanic history of Earth’s sibling, and indirectly speaks towards how Venus became so hot in the first place. </p>
<p>The starting point to understanding Venus is the climate. The average surface temperature is 460°C – far too hot for liquid water and above the <a href="http://www.bbc.co.uk/earth/story/20160209-this-is-how-to-survive-if-you-spend-your-life-in-boilin-water">known thermal limit</a> for life, which is roughly 122°C. </p>
<p>This extreme heat is not simply because Venus is closer to the Sun, but also because it is enveloped by an über-greenhouse atmosphere. At 92 times the pressure of that on Earth, it’s enough to crush modern submarines. If you were standing on the Venusian surface it would be like swimming 1,000 metres below sea level – if the oceans were 460°C, that is. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/171350/original/file-20170529-25203-te8f7z.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/171350/original/file-20170529-25203-te8f7z.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/171350/original/file-20170529-25203-te8f7z.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/171350/original/file-20170529-25203-te8f7z.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/171350/original/file-20170529-25203-te8f7z.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/171350/original/file-20170529-25203-te8f7z.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/171350/original/file-20170529-25203-te8f7z.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/171350/original/file-20170529-25203-te8f7z.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">It ain’t half hot, mum.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/smile-crazy-scuba-diver-underwater-selfie-517820569?src=_2NAPKyoHbIWerQe60NRbw-1-85">Andrea Izzotti</a></span>
</figcaption>
</figure>
<p>The scorching temperature of Venus’s surface has many knock-on effects. It means, for example, that there’s no Earth-like plate tectonics. Most of the crust is too soft to snap, and it “<a href="https://www.nature.com/nature/journal/v508/n7497/full/nature13072.html">heals</a>” when broken. There have recently been suggestions that the planet might either have its <a href="http://www.nature.com/ngeo/journal/v10/n5/full/ngeo2928.html">own alternative version</a> of plate tectonics, <a href="http://www.sciencedirect.com/science/article/pii/S0032063315000409">or that</a> the high surface temperature results in the Venusian crust being physically decoupled from mantle flow beneath. At any rate, where plate tectonics <a href="http://www.sciencedirect.com/science/article/pii/B9780123964533000010">is behind</a> 90% of volcanic eruptions on Earth, this is not the case on Venus. </p>
<p>Venus does have volcanoes, but they’re all of the variety we call <a href="https://www.britannica.com/science/intraplate-volcanism">intra-plate or hotspots</a>, where plumes of magma rise up from the mantle and push their way to the surface via cracks in the crust. To study them, we compared them to the ones on Earth. We only considered volcanoes situated on Earth’s oceanic crust, since it is more comparable to the Venusian crust. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/171355/original/file-20170529-25203-i4zq4o.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/171355/original/file-20170529-25203-i4zq4o.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/171355/original/file-20170529-25203-i4zq4o.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=410&fit=crop&dpr=1 600w, https://images.theconversation.com/files/171355/original/file-20170529-25203-i4zq4o.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=410&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/171355/original/file-20170529-25203-i4zq4o.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=410&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/171355/original/file-20170529-25203-i4zq4o.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=516&fit=crop&dpr=1 754w, https://images.theconversation.com/files/171355/original/file-20170529-25203-i4zq4o.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=516&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/171355/original/file-20170529-25203-i4zq4o.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=516&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Kilauea in Hawaii, one of Earth’s hotspot volcanoes.</span>
<span class="attribution"><a class="source" href="https://en.wikipedia.org/wiki/Kīlauea#/media/File:Puu_Oo_cropped.jpg">Wikimedia</a></span>
</figcaption>
</figure>
<p>The oceanic crust covers 60% of Earth’s surface. It is host to more than 100,000 hotspot volcanoes that have formed in less than 100m years. Conversely, Venus’ entire surface has produced only 70,000 individual volcanoes over a period of some 700m years (give or take 300m) – roughly the age of its outer crust. In other words, the difference in the rate of intra-plate volcano production is roughly ten times. (And bear in mind this is a comparison against only a small minority of the total number of volcanoes on Earth since it was formed.) </p>
<h2>Time travelling with argon</h2>
<p>To investigate whether Venus was always so volcanically challenged over its approximately 4.6 billion-year history, we called on the services of argon (Ar). This noble gas comes in three “flavours”, each with a slightly different mass (36, 38 and 40). We know that when Venus and Earth formed, 99% of their argon-36 and argon-38 quickly ended up in the air. </p>
<p>On the other hand, the argon-40 was only able to emerge slowly from the decay of an isotope of potassium that is stored in rocks. To find its way into the air, it then needed a mechanism to transport it there – the most efficient being volcanism. Because Earth’s atmosphere nowadays contains significantly more argon-40 than Venus’s, we can therefore assume Venus has been less volcanically active for its entire existence. </p>
<p>This conclusion probably sounds counter-intuitive – you might expect a hotter planet to be more volcanically active, not less so. When we studied this using rock deformation data, we found a similar phenomenon to the one that prevents plate tectonics on Venus. Because the crust is more like Play-Doh than the toffee brittle of Earth’s crust, it is difficult for magma to move through cracks and form volcanoes. On Venus, we predict, that most magma gets stuck in the Play-Doh – as you can see from the diagram below. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/171347/original/file-20170529-25236-1yqojwt.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/171347/original/file-20170529-25236-1yqojwt.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/171347/original/file-20170529-25236-1yqojwt.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=282&fit=crop&dpr=1 600w, https://images.theconversation.com/files/171347/original/file-20170529-25236-1yqojwt.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=282&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/171347/original/file-20170529-25236-1yqojwt.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=282&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/171347/original/file-20170529-25236-1yqojwt.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=355&fit=crop&dpr=1 754w, https://images.theconversation.com/files/171347/original/file-20170529-25236-1yqojwt.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=355&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/171347/original/file-20170529-25236-1yqojwt.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=355&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption"></span>
</figcaption>
</figure>
<p>Incidentally, this lack of argon-40 in Venus’ atmosphere also probably explains why the planet has never had oceans. This is because the decaying potassium-40 that produces argon-40 exists within silicate minerals. Importantly, the crystal structure of silicate minerals also contains hydroxide anions, which is essentially water. </p>
<p>Indeed, the silicate mantles of both planets <a href="https://deepcarbon.net/feature/water-earth%E2%80%99s-transition-zone-directly-measured#.WSxiwTOZPeQ">can store</a> more than six times the mass of water present in Earth’s oceans. In other words, Earth’s volcanoes not only pumped out life-giving air, but also our oceans. </p>
<p>Furthermore, the great difference in the number of volcanoes may explain the runaway greenhouse effect on Venus. This is because fresh basalt exposed by volcanic eruptions can react with liquid water through a series of chemical reactions known as <a href="http://science.sciencemag.org/content/344/6182/373">carbonation</a> to remove carbon dioxide from the atmosphere. It is an excess of carbon dioxide that is responsible for the greenhouse effect. In short, it is no exaggeration to suggest that volcanoes may explain most of the fundamental differences between Earth and Venus. </p>
<p>For those of us at the <a href="https://www.st-andrews.ac.uk/exoplanets/index.html">St Andrews Centre for Exoplanet Science</a>, we’ll now return to the big picture. We aim to shed more light on how planets become habitable, and how to spot an Earth from a Venus at a distance so great it’s measured in light years. It’s certainly difficult doing this from Earth, but with a great set of PhD students, postdoctoral fellows and an open mind, I am confident we will get to the bottom of it.</p><img src="https://counter.theconversation.com/content/78363/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Sami Mikhail receives funding from the Natural Environment Research Council (NE/P012167/1).</span></em></p>The planet is more similar to Earth than any other – except when it comes to supporting life.Sami Mikhail, Lecturer in Earth Sciences and Environmental Sciences & the Center for Exoplanet Science, University of St AndrewsLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/677252016-10-27T14:06:20Z2016-10-27T14:06:20ZMagma power: how superheated molten rock could provide renewable energy<figure><img src="https://images.theconversation.com/files/143298/original/image-20161026-11265-1b7ixuo.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Magma is molten rock below the Earth's surface. Once erupted, it becomes lava (pictured).</span> <span class="attribution"><span class="source">Benjamin van der Spek / shutterstock</span></span></figcaption></figure><p>Iceland is about to tap into water as hot as lava. Several kilometres below ground, a drilling rig named Thor will <a href="https://www.newscientist.com/article/2109872-iceland-drills-hottest-hole-to-tap-into-energy-of-molten-magma/">soon penetrate</a> the area around a magma chamber, where molten rock from the inner Earth heats up water that has seeped through the seafloor. This water – up to 1,000°C and saturated with corrosive chemicals – will eventually be piped up to the surface and its heat turned into usable energy.</p>
<p>It is a huge engineering challenge, and one which may usher in a new age of geothermal power production. Existing geothermal projects around the world need waters heated to less than 300°C, so why go to this extra effort and expense?</p>
<p>The answer is simple: water at the most extreme temperatures exists in a state described as “<a href="http://www.nottingham.ac.uk/supercritical/scintro.html">supercritical</a>”, where it behaves as neither a true liquid, nor a true gas, and is capable of retaining a phenomenal amount of energy. Supercritical water can generate up to <a href="http://sciencenordic.com/drilling-worlds-hottest-geothermal-well">ten times more power</a> than conventional geothermal sources.</p>
<p>Iceland is a nation built on about 130 volcanoes resting above a <a href="http://oceanexplorer.noaa.gov/facts/plate-boundaries.html">divergent plate boundary</a> which brings a continuous supply of hot, fresh magma up from the mantle just a few kilometres below. Icelanders have capitalised on this, and now generate more than a quarter of their electricity through <a href="http://www.nea.is/media/myndir/popup/Iceland_Leader_RenewableEnergy_Mynd.png">geothermal</a>, accessing boiling temperature water within 2km of the surface.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/143297/original/image-20161026-11278-z24o5.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/143297/original/image-20161026-11278-z24o5.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/143297/original/image-20161026-11278-z24o5.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/143297/original/image-20161026-11278-z24o5.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/143297/original/image-20161026-11278-z24o5.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/143297/original/image-20161026-11278-z24o5.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/143297/original/image-20161026-11278-z24o5.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/143297/original/image-20161026-11278-z24o5.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Iceland is happy to exploit its unusual geology.</span>
<span class="attribution"><span class="source">Jose Arcos Aguilar / shutterstock</span></span>
</figcaption>
</figure>
<p>The <a href="http://iddp.is/">Iceland Deep Drilling Project</a> (IDDP) was set up to find out what happens at depths below 4km in the Icelandic crust. In 2009, during their first drilling leg, they accidentally <a href="https://theconversation.com/drilling-surprise-opens-door-to-volcano-powered-electricity-22515">hit a magma pocket</a>, and eventually stabilised the system to create the <a href="https://www.youtube.com/watch?v=3d8hC71xGpc">hottest steam</a> ever produced in geothermal exploration: 450°C. </p>
<p>The second borehole now being drilled aims to tap the deep circulating water which penetrates the rock around a magma chamber below the Reykjanes peninsula near Reykjavik.</p>
<h2>Follow the volcanoes</h2>
<p>The embarrassment of geothermal riches on offer in Iceland is unusual, but by no means unique. Indeed, while the country has one of the highest geothermal electricity productions in terms of total energy share, it is neither the highest, nor is it in the top five countries for total geothermal capacity. In fact, the countries in the top five may come as a surprise.</p>
<p>The absolute biggest geothermal electricity producer in the world is the US, <a href="https://pangea.stanford.edu/ERE/db/WGC/papers/WGC/2015/01001.pdf">with around 3,450 MW of capacity in 2015</a>, largely centred in California (a typical nuclear power station produces around 1,000 MW). Next up are the Philippines and Indonesia, at 1,870 and 1,340 MW respectively. Mexico and New Zealand trail at a little over 1,000 MW each, and Iceland (665 MW) comes in seventh behind Italy (916 MW). </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/143300/original/image-20161026-11265-10libvz.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/143300/original/image-20161026-11265-10libvz.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/143300/original/image-20161026-11265-10libvz.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=302&fit=crop&dpr=1 600w, https://images.theconversation.com/files/143300/original/image-20161026-11265-10libvz.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=302&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/143300/original/image-20161026-11265-10libvz.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=302&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/143300/original/image-20161026-11265-10libvz.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=379&fit=crop&dpr=1 754w, https://images.theconversation.com/files/143300/original/image-20161026-11265-10libvz.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=379&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/143300/original/image-20161026-11265-10libvz.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=379&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Geothermal energy will usually be found near active volcanoes.</span>
<span class="attribution"><a class="source" href="https://commons.wikimedia.org/wiki/File:Spreading_ridges_volcanoes_map-en.svg">Eric Gaba</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
</figcaption>
</figure>
<p>Volcanoes are the common factor in the geothermal resources of all these countries. The US has also utilised the enormous San Andreas fault zone and its ability to conduct heat and fluids through the crust.</p>
<h2>In search of the perfect geothermal site</h2>
<p>For geothermal energy to succeed there must be heat, it must be accessible, and you must be able to move water around it. These three simple requirements can be difficult to find together. </p>
<p>Across most of the planet the hot material is simply too deep down to be economically within reach. The temperature of the Earth’s crust generally increases by <a href="http://www.geologyin.com/2014/12/geothermal-gradient.html">25°C for every 1km depth</a>; for geothermal to be economical that value must be nearer 50 or even 150°C/km. That means you need to be near something geologically unusual: either thinned crust (so you’re closer to the hot mantle), or features such as plate boundaries or volcanoes which can direct heat or magma toward the surface.</p>
<p>If that condition is met you must still be able to move water around. Rocks are not all alike, as some can allow water to easily flow through the pores and boundaries between grains, while others are more like a barrier. If water cannot flow to the borehole then it cannot be brought to the surface. </p>
<p>If the hot area doesn’t have any natural water then engineers can pump some down. However, if the rocks prevent it flowing and dispersing then the water will simply cool the area immediately around the borehole, making it pointless in geothermal terms.</p>
<p>As with gold, rare-earth elements or good farmland, the geology of an area controls access to this valuable resource. Anywhere with active volcanoes could potentially benefit from the high temperature geothermal exploration being pioneered by the IDDP. That includes every country around the Pacific <a href="http://nationalgeographic.org/encyclopedia/ring-fire/">Ring of Fire</a> – an opportunity perhaps to extract some benefit from the volcanoes which dot their landscapes.</p><img src="https://counter.theconversation.com/content/67725/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Pete Rowley does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>In Iceland, an audacious project to tap into magma deep below the surface may usher in a new era of geothermal power.Pete Rowley, Senior Scientific Officer, Earth Science, University of PortsmouthLicensed as Creative Commons – attribution, no derivatives.